Rename extensions/ directory to ext/ (#11643)

5 files changed, 1457 insertions, 0 deletions

diff --git a/ext/webidl/00_webidl.js b/ext/webidl/00_webidl.js
new file mode 100644
index 000000000..40250afe1
--- /dev/null
+++ b/ext/webidl/00_webidl.js
@@ -0,0 +1,1079 @@
+// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
+
+// Adapted from https://github.com/jsdom/webidl-conversions.
+// Copyright Domenic Denicola. Licensed under BSD-2-Clause License.
+// Original license at https://github.com/jsdom/webidl-conversions/blob/master/LICENSE.md.
+
+/// <reference path="../../core/internal.d.ts" />
+
+"use strict";
+
+((window) => {
+  const {
+    ArrayBuffer,
+    ArrayBufferIsView,
+    ArrayPrototypeForEach,
+    ArrayPrototypePush,
+    ArrayPrototypeSort,
+    ArrayIteratorPrototype,
+    BigInt,
+    BigIntAsIntN,
+    BigIntAsUintN,
+    DataView,
+    Float32Array,
+    Float64Array,
+    FunctionPrototypeBind,
+    Int16Array,
+    Int32Array,
+    Int8Array,
+    isNaN,
+    MathFloor,
+    MathFround,
+    MathMax,
+    MathMin,
+    MathPow,
+    MathRound,
+    MathTrunc,
+    Number,
+    NumberIsFinite,
+    NumberIsNaN,
+    // deno-lint-ignore camelcase
+    NumberMAX_SAFE_INTEGER,
+    // deno-lint-ignore camelcase
+    NumberMIN_SAFE_INTEGER,
+    ObjectCreate,
+    ObjectDefineProperties,
+    ObjectDefineProperty,
+    ObjectGetOwnPropertyDescriptor,
+    ObjectGetOwnPropertyDescriptors,
+    ObjectGetPrototypeOf,
+    ObjectIs,
+    PromisePrototypeThen,
+    PromiseReject,
+    PromiseResolve,
+    ReflectApply,
+    ReflectDefineProperty,
+    ReflectGetOwnPropertyDescriptor,
+    ReflectOwnKeys,
+    RegExpPrototypeTest,
+    Set,
+    // TODO(lucacasonato): add SharedArrayBuffer to primordials
+    // SharedArrayBuffer,
+    String,
+    StringFromCodePoint,
+    StringPrototypeCharCodeAt,
+    StringPrototypeCodePointAt,
+    Symbol,
+    SymbolIterator,
+    SymbolToStringTag,
+    TypeError,
+    Uint16Array,
+    Uint32Array,
+    Uint8Array,
+    Uint8ClampedArray,
+  } = window.__bootstrap.primordials;
+
+  function makeException(ErrorType, message, opts = {}) {
+    return new ErrorType(
+      `${opts.prefix ? opts.prefix + ": " : ""}${
+        opts.context ? opts.context : "Value"
+      } ${message}`,
+    );
+  }
+
+  function toNumber(value) {
+    if (typeof value === "bigint") {
+      throw TypeError("Cannot convert a BigInt value to a number");
+    }
+    return Number(value);
+  }
+
+  function type(V) {
+    if (V === null) {
+      return "Null";
+    }
+    switch (typeof V) {
+      case "undefined":
+        return "Undefined";
+      case "boolean":
+        return "Boolean";
+      case "number":
+        return "Number";
+      case "string":
+        return "String";
+      case "symbol":
+        return "Symbol";
+      case "bigint":
+        return "BigInt";
+      case "object":
+      // Falls through
+      case "function":
+      // Falls through
+      default:
+        // Per ES spec, typeof returns an implemention-defined value that is not any of the existing ones for
+        // uncallable non-standard exotic objects. Yet Type() which the Web IDL spec depends on returns Object for
+        // such cases. So treat the default case as an object.
+        return "Object";
+    }
+  }
+
+  // Round x to the nearest integer, choosing the even integer if it lies halfway between two.
+  function evenRound(x) {
+    // There are four cases for numbers with fractional part being .5:
+    //
+    // case |     x     | floor(x) | round(x) | expected | x <> 0 | x % 1 | x & 1 |   example
+    //   1  |  2n + 0.5 |  2n      |  2n + 1  |  2n      |   >    |  0.5  |   0   |  0.5 ->  0
+    //   2  |  2n + 1.5 |  2n + 1  |  2n + 2  |  2n + 2  |   >    |  0.5  |   1   |  1.5 ->  2
+    //   3  | -2n - 0.5 | -2n - 1  | -2n      | -2n      |   <    | -0.5  |   0   | -0.5 ->  0
+    //   4  | -2n - 1.5 | -2n - 2  | -2n - 1  | -2n - 2  |   <    | -0.5  |   1   | -1.5 -> -2
+    // (where n is a non-negative integer)
+    //
+    // Branch here for cases 1 and 4
+    if (
+      (x > 0 && x % 1 === +0.5 && (x & 1) === 0) ||
+      (x < 0 && x % 1 === -0.5 && (x & 1) === 1)
+    ) {
+      return censorNegativeZero(MathFloor(x));
+    }
+
+    return censorNegativeZero(MathRound(x));
+  }
+
+  function integerPart(n) {
+    return censorNegativeZero(MathTrunc(n));
+  }
+
+  function sign(x) {
+    return x < 0 ? -1 : 1;
+  }
+
+  function modulo(x, y) {
+    // https://tc39.github.io/ecma262/#eqn-modulo
+    // Note that http://stackoverflow.com/a/4467559/3191 does NOT work for large modulos
+    const signMightNotMatch = x % y;
+    if (sign(y) !== sign(signMightNotMatch)) {
+      return signMightNotMatch + y;
+    }
+    return signMightNotMatch;
+  }
+
+  function censorNegativeZero(x) {
+    return x === 0 ? 0 : x;
+  }
+
+  function createIntegerConversion(bitLength, typeOpts) {
+    const isSigned = !typeOpts.unsigned;
+
+    let lowerBound;
+    let upperBound;
+    if (bitLength === 64) {
+      upperBound = NumberMAX_SAFE_INTEGER;
+      lowerBound = !isSigned ? 0 : NumberMIN_SAFE_INTEGER;
+    } else if (!isSigned) {
+      lowerBound = 0;
+      upperBound = MathPow(2, bitLength) - 1;
+    } else {
+      lowerBound = -MathPow(2, bitLength - 1);
+      upperBound = MathPow(2, bitLength - 1) - 1;
+    }
+
+    const twoToTheBitLength = MathPow(2, bitLength);
+    const twoToOneLessThanTheBitLength = MathPow(2, bitLength - 1);
+
+    return (V, opts = {}) => {
+      let x = toNumber(V, opts);
+      x = censorNegativeZero(x);
+
+      if (opts.enforceRange) {
+        if (!NumberIsFinite(x)) {
+          throw makeException(TypeError, "is not a finite number", opts);
+        }
+
+        x = integerPart(x);
+
+        if (x < lowerBound || x > upperBound) {
+          throw makeException(
+            TypeError,
+            `is outside the accepted range of ${lowerBound} to ${upperBound}, inclusive`,
+            opts,
+          );
+        }
+
+        return x;
+      }
+
+      if (!NumberIsNaN(x) && opts.clamp) {
+        x = MathMin(MathMax(x, lowerBound), upperBound);
+        x = evenRound(x);
+        return x;
+      }
+
+      if (!NumberIsFinite(x) || x === 0) {
+        return 0;
+      }
+      x = integerPart(x);
+
+      // Math.pow(2, 64) is not accurately representable in JavaScript, so try to avoid these per-spec operations if
+      // possible. Hopefully it's an optimization for the non-64-bitLength cases too.
+      if (x >= lowerBound && x <= upperBound) {
+        return x;
+      }
+
+      // These will not work great for bitLength of 64, but oh well. See the README for more details.
+      x = modulo(x, twoToTheBitLength);
+      if (isSigned && x >= twoToOneLessThanTheBitLength) {
+        return x - twoToTheBitLength;
+      }
+      return x;
+    };
+  }
+
+  function createLongLongConversion(bitLength, { unsigned }) {
+    const upperBound = NumberMAX_SAFE_INTEGER;
+    const lowerBound = unsigned ? 0 : NumberMIN_SAFE_INTEGER;
+    const asBigIntN = unsigned ? BigIntAsUintN : BigIntAsIntN;
+
+    return (V, opts = {}) => {
+      let x = toNumber(V, opts);
+      x = censorNegativeZero(x);
+
+      if (opts.enforceRange) {
+        if (!NumberIsFinite(x)) {
+          throw makeException(TypeError, "is not a finite number", opts);
+        }
+
+        x = integerPart(x);
+
+        if (x < lowerBound || x > upperBound) {
+          throw makeException(
+            TypeError,
+            `is outside the accepted range of ${lowerBound} to ${upperBound}, inclusive`,
+            opts,
+          );
+        }
+
+        return x;
+      }
+
+      if (!NumberIsNaN(x) && opts.clamp) {
+        x = MathMin(MathMax(x, lowerBound), upperBound);
+        x = evenRound(x);
+        return x;
+      }
+
+      if (!NumberIsFinite(x) || x === 0) {
+        return 0;
+      }
+
+      let xBigInt = BigInt(integerPart(x));
+      xBigInt = asBigIntN(bitLength, xBigInt);
+      return Number(xBigInt);
+    };
+  }
+
+  const converters = [];
+
+  converters.any = (V) => {
+    return V;
+  };
+
+  converters.boolean = function (val) {
+    return !!val;
+  };
+
+  converters.byte = createIntegerConversion(8, { unsigned: false });
+  converters.octet = createIntegerConversion(8, { unsigned: true });
+
+  converters.short = createIntegerConversion(16, { unsigned: false });
+  converters["unsigned short"] = createIntegerConversion(16, {
+    unsigned: true,
+  });
+
+  converters.long = createIntegerConversion(32, { unsigned: false });
+  converters["unsigned long"] = createIntegerConversion(32, { unsigned: true });
+
+  converters["long long"] = createLongLongConversion(64, { unsigned: false });
+  converters["unsigned long long"] = createLongLongConversion(64, {
+    unsigned: true,
+  });
+
+  converters.float = (V, opts) => {
+    const x = toNumber(V, opts);
+
+    if (!NumberIsFinite(x)) {
+      throw makeException(
+        TypeError,
+        "is not a finite floating-point value",
+        opts,
+      );
+    }
+
+    if (ObjectIs(x, -0)) {
+      return x;
+    }
+
+    const y = MathFround(x);
+
+    if (!NumberIsFinite(y)) {
+      throw makeException(
+        TypeError,
+        "is outside the range of a single-precision floating-point value",
+        opts,
+      );
+    }
+
+    return y;
+  };
+
+  converters["unrestricted float"] = (V, opts) => {
+    const x = toNumber(V, opts);
+
+    if (isNaN(x)) {
+      return x;
+    }
+
+    if (ObjectIs(x, -0)) {
+      return x;
+    }
+
+    return MathFround(x);
+  };
+
+  converters.double = (V, opts) => {
+    const x = toNumber(V, opts);
+
+    if (!NumberIsFinite(x)) {
+      throw makeException(
+        TypeError,
+        "is not a finite floating-point value",
+        opts,
+      );
+    }
+
+    return x;
+  };
+
+  converters["unrestricted double"] = (V, opts) => {
+    const x = toNumber(V, opts);
+
+    return x;
+  };
+
+  converters.DOMString = function (V, opts = {}) {
+    if (opts.treatNullAsEmptyString && V === null) {
+      return "";
+    }
+
+    if (typeof V === "symbol") {
+      throw makeException(
+        TypeError,
+        "is a symbol, which cannot be converted to a string",
+        opts,
+      );
+    }
+
+    return String(V);
+  };
+
+  converters.ByteString = (V, opts) => {
+    const x = converters.DOMString(V, opts);
+    let c;
+    for (let i = 0; (c = StringPrototypeCodePointAt(x, i)) !== undefined; ++i) {
+      if (c > 255) {
+        throw makeException(TypeError, "is not a valid ByteString", opts);
+      }
+    }
+
+    return x;
+  };
+
+  converters.USVString = (V, opts) => {
+    const S = converters.DOMString(V, opts);
+    const n = S.length;
+    let U = "";
+    for (let i = 0; i < n; ++i) {
+      const c = StringPrototypeCharCodeAt(S, i);
+      if (c < 0xd800 || c > 0xdfff) {
+        U += StringFromCodePoint(c);
+      } else if (0xdc00 <= c && c <= 0xdfff) {
+        U += StringFromCodePoint(0xfffd);
+      } else if (i === n - 1) {
+        U += StringFromCodePoint(0xfffd);
+      } else {
+        const d = StringPrototypeCharCodeAt(S, i + 1);
+        if (0xdc00 <= d && d <= 0xdfff) {
+          const a = c & 0x3ff;
+          const b = d & 0x3ff;
+          U += StringFromCodePoint((2 << 15) + (2 << 9) * a + b);
+          ++i;
+        } else {
+          U += StringFromCodePoint(0xfffd);
+        }
+      }
+    }
+    return U;
+  };
+
+  converters.object = (V, opts) => {
+    if (type(V) !== "Object") {
+      throw makeException(TypeError, "is not an object", opts);
+    }
+
+    return V;
+  };
+
+  // Not exported, but used in Function and VoidFunction.
+
+  // Neither Function nor VoidFunction is defined with [TreatNonObjectAsNull], so
+  // handling for that is omitted.
+  function convertCallbackFunction(V, opts) {
+    if (typeof V !== "function") {
+      throw makeException(TypeError, "is not a function", opts);
+    }
+    return V;
+  }
+
+  function isNonSharedArrayBuffer(V) {
+    return V instanceof ArrayBuffer;
+  }
+
+  function isSharedArrayBuffer(V) {
+    return V instanceof SharedArrayBuffer;
+  }
+
+  function isArrayBufferDetached(V) {
+    try {
+      new Uint8Array(V);
+      return false;
+    } catch {
+      return true;
+    }
+  }
+
+  converters.ArrayBuffer = (V, opts = {}) => {
+    if (!isNonSharedArrayBuffer(V)) {
+      if (opts.allowShared && !isSharedArrayBuffer(V)) {
+        throw makeException(
+          TypeError,
+          "is not an ArrayBuffer or SharedArrayBuffer",
+          opts,
+        );
+      }
+      throw makeException(TypeError, "is not an ArrayBuffer", opts);
+    }
+    if (isArrayBufferDetached(V)) {
+      throw makeException(TypeError, "is a detached ArrayBuffer", opts);
+    }
+
+    return V;
+  };
+
+  converters.DataView = (V, opts = {}) => {
+    if (!(V instanceof DataView)) {
+      throw makeException(TypeError, "is not a DataView", opts);
+    }
+
+    if (!opts.allowShared && isSharedArrayBuffer(V.buffer)) {
+      throw makeException(
+        TypeError,
+        "is backed by a SharedArrayBuffer, which is not allowed",
+        opts,
+      );
+    }
+    if (isArrayBufferDetached(V.buffer)) {
+      throw makeException(
+        TypeError,
+        "is backed by a detached ArrayBuffer",
+        opts,
+      );
+    }
+
+    return V;
+  };
+
+  // Returns the unforgeable `TypedArray` constructor name or `undefined`,
+  // if the `this` value isn't a valid `TypedArray` object.
+  //
+  // https://tc39.es/ecma262/#sec-get-%typedarray%.prototype-@@tostringtag
+  const typedArrayNameGetter = ObjectGetOwnPropertyDescriptor(
+    ObjectGetPrototypeOf(Uint8Array).prototype,
+    SymbolToStringTag,
+  ).get;
+  ArrayPrototypeForEach(
+    [
+      Int8Array,
+      Int16Array,
+      Int32Array,
+      Uint8Array,
+      Uint16Array,
+      Uint32Array,
+      Uint8ClampedArray,
+      Float32Array,
+      Float64Array,
+    ],
+    (func) => {
+      const name = func.name;
+      const article = RegExpPrototypeTest(/^[AEIOU]/, name) ? "an" : "a";
+      converters[name] = (V, opts = {}) => {
+        if (!ArrayBufferIsView(V) || typedArrayNameGetter.call(V) !== name) {
+          throw makeException(
+            TypeError,
+            `is not ${article} ${name} object`,
+            opts,
+          );
+        }
+        if (!opts.allowShared && isSharedArrayBuffer(V.buffer)) {
+          throw makeException(
+            TypeError,
+            "is a view on a SharedArrayBuffer, which is not allowed",
+            opts,
+          );
+        }
+        if (isArrayBufferDetached(V.buffer)) {
+          throw makeException(
+            TypeError,
+            "is a view on a detached ArrayBuffer",
+            opts,
+          );
+        }
+
+        return V;
+      };
+    },
+  );
+
+  // Common definitions
+
+  converters.ArrayBufferView = (V, opts = {}) => {
+    if (!ArrayBufferIsView(V)) {
+      throw makeException(
+        TypeError,
+        "is not a view on an ArrayBuffer or SharedArrayBuffer",
+        opts,
+      );
+    }
+
+    if (!opts.allowShared && isSharedArrayBuffer(V.buffer)) {
+      throw makeException(
+        TypeError,
+        "is a view on a SharedArrayBuffer, which is not allowed",
+        opts,
+      );
+    }
+
+    if (isArrayBufferDetached(V.buffer)) {
+      throw makeException(
+        TypeError,
+        "is a view on a detached ArrayBuffer",
+        opts,
+      );
+    }
+    return V;
+  };
+
+  converters.BufferSource = (V, opts = {}) => {
+    if (ArrayBufferIsView(V)) {
+      if (!opts.allowShared && isSharedArrayBuffer(V.buffer)) {
+        throw makeException(
+          TypeError,
+          "is a view on a SharedArrayBuffer, which is not allowed",
+          opts,
+        );
+      }
+
+      if (isArrayBufferDetached(V.buffer)) {
+        throw makeException(
+          TypeError,
+          "is a view on a detached ArrayBuffer",
+          opts,
+        );
+      }
+      return V;
+    }
+
+    if (!opts.allowShared && !isNonSharedArrayBuffer(V)) {
+      throw makeException(
+        TypeError,
+        "is not an ArrayBuffer or a view on one",
+        opts,
+      );
+    }
+    if (
+      opts.allowShared &&
+      !isSharedArrayBuffer(V) &&
+      !isNonSharedArrayBuffer(V)
+    ) {
+      throw makeException(
+        TypeError,
+        "is not an ArrayBuffer, SharedArrayBuffer, or a view on one",
+        opts,
+      );
+    }
+    if (isArrayBufferDetached(V)) {
+      throw makeException(TypeError, "is a detached ArrayBuffer", opts);
+    }
+
+    return V;
+  };
+
+  converters.DOMTimeStamp = converters["unsigned long long"];
+  converters.DOMHighResTimeStamp = converters["double"];
+
+  converters.Function = convertCallbackFunction;
+
+  converters.VoidFunction = convertCallbackFunction;
+
+  converters["UVString?"] = createNullableConverter(
+    converters.USVString,
+  );
+  converters["sequence<double>"] = createSequenceConverter(
+    converters.double,
+  );
+  converters["sequence<object>"] = createSequenceConverter(
+    converters.object,
+  );
+  converters["Promise<undefined>"] = createPromiseConverter(() => undefined);
+
+  converters["sequence<ByteString>"] = createSequenceConverter(
+    converters.ByteString,
+  );
+  converters["sequence<sequence<ByteString>>"] = createSequenceConverter(
+    converters["sequence<ByteString>"],
+  );
+  converters["record<ByteString, ByteString>"] = createRecordConverter(
+    converters.ByteString,
+    converters.ByteString,
+  );
+
+  converters["sequence<USVString>"] = createSequenceConverter(
+    converters.USVString,
+  );
+  converters["sequence<sequence<USVString>>"] = createSequenceConverter(
+    converters["sequence<USVString>"],
+  );
+  converters["record<USVString, USVString>"] = createRecordConverter(
+    converters.USVString,
+    converters.USVString,
+  );
+
+  converters["sequence<DOMString>"] = createSequenceConverter(
+    converters.DOMString,
+  );
+
+  function requiredArguments(length, required, opts = {}) {
+    if (length < required) {
+      const errMsg = `${
+        opts.prefix ? opts.prefix + ": " : ""
+      }${required} argument${
+        required === 1 ? "" : "s"
+      } required, but only ${length} present.`;
+      throw new TypeError(errMsg);
+    }
+  }
+
+  function createDictionaryConverter(name, ...dictionaries) {
+    let hasRequiredKey = false;
+    const allMembers = [];
+    for (const members of dictionaries) {
+      for (const member of members) {
+        if (member.required) {
+          hasRequiredKey = true;
+        }
+        ArrayPrototypePush(allMembers, member);
+      }
+    }
+    ArrayPrototypeSort(allMembers, (a, b) => {
+      if (a.key == b.key) {
+        return 0;
+      }
+      return a.key < b.key ? -1 : 1;
+    });
+
+    const defaultValues = {};
+    for (const member of allMembers) {
+      if ("defaultValue" in member) {
+        const idlMemberValue = member.defaultValue;
+        const imvType = typeof idlMemberValue;
+        // Copy by value types can be directly assigned, copy by reference types
+        // need to be re-created for each allocation.
+        if (
+          imvType === "number" || imvType === "boolean" ||
+          imvType === "string" || imvType === "bigint" ||
+          imvType === "undefined"
+        ) {
+          defaultValues[member.key] = idlMemberValue;
+        } else {
+          ObjectDefineProperty(defaultValues, member.key, {
+            get() {
+              return member.defaultValue;
+            },
+            enumerable: true,
+          });
+        }
+      }
+    }
+
+    return function (V, opts = {}) {
+      const typeV = type(V);
+      switch (typeV) {
+        case "Undefined":
+        case "Null":
+        case "Object":
+          break;
+        default:
+          throw makeException(
+            TypeError,
+            "can not be converted to a dictionary",
+            opts,
+          );
+      }
+      const esDict = V;
+
+      const idlDict = { ...defaultValues };
+
+      // NOTE: fast path Null and Undefined.
+      if ((V === undefined || V === null) && !hasRequiredKey) {
+        return idlDict;
+      }
+
+      for (const member of allMembers) {
+        const key = member.key;
+
+        let esMemberValue;
+        if (typeV === "Undefined" || typeV === "Null") {
+          esMemberValue = undefined;
+        } else {
+          esMemberValue = esDict[key];
+        }
+
+        if (esMemberValue !== undefined) {
+          const context = `'${key}' of '${name}'${
+            opts.context ? ` (${opts.context})` : ""
+          }`;
+          const converter = member.converter;
+          const idlMemberValue = converter(esMemberValue, { ...opts, context });
+          idlDict[key] = idlMemberValue;
+        } else if (member.required) {
+          throw makeException(
+            TypeError,
+            `can not be converted to '${name}' because '${key}' is required in '${name}'.`,
+            { ...opts },
+          );
+        }
+      }
+
+      return idlDict;
+    };
+  }
+
+  // https://heycam.github.io/webidl/#es-enumeration
+  function createEnumConverter(name, values) {
+    const E = new Set(values);
+
+    return function (V, opts = {}) {
+      const S = String(V);
+
+      if (!E.has(S)) {
+        throw new TypeError(
+          `${
+            opts.prefix ? opts.prefix + ": " : ""
+          }The provided value '${S}' is not a valid enum value of type ${name}.`,
+        );
+      }
+
+      return S;
+    };
+  }
+
+  function createNullableConverter(converter) {
+    return (V, opts = {}) => {
+      // FIXME: If Type(V) is not Object, and the conversion to an IDL value is
+      // being performed due to V being assigned to an attribute whose type is a
+      // nullable callback function that is annotated with
+      // [LegacyTreatNonObjectAsNull], then return the IDL nullable type T?
+      // value null.
+
+      if (V === null || V === undefined) return null;
+      return converter(V, opts);
+    };
+  }
+
+  // https://heycam.github.io/webidl/#es-sequence
+  function createSequenceConverter(converter) {
+    return function (V, opts = {}) {
+      if (type(V) !== "Object") {
+        throw makeException(
+          TypeError,
+          "can not be converted to sequence.",
+          opts,
+        );
+      }
+      const iter = V?.[SymbolIterator]?.();
+      if (iter === undefined) {
+        throw makeException(
+          TypeError,
+          "can not be converted to sequence.",
+          opts,
+        );
+      }
+      const array = [];
+      while (true) {
+        const res = iter?.next?.();
+        if (res === undefined) {
+          throw makeException(
+            TypeError,
+            "can not be converted to sequence.",
+            opts,
+          );
+        }
+        if (res.done === true) break;
+        const val = converter(res.value, {
+          ...opts,
+          context: `${opts.context}, index ${array.length}`,
+        });
+        ArrayPrototypePush(array, val);
+      }
+      return array;
+    };
+  }
+
+  function createRecordConverter(keyConverter, valueConverter) {
+    return (V, opts) => {
+      if (type(V) !== "Object") {
+        throw makeException(
+          TypeError,
+          "can not be converted to dictionary.",
+          opts,
+        );
+      }
+      const keys = ReflectOwnKeys(V);
+      const result = {};
+      for (const key of keys) {
+        const desc = ObjectGetOwnPropertyDescriptor(V, key);
+        if (desc !== undefined && desc.enumerable === true) {
+          const typedKey = keyConverter(key, opts);
+          const value = V[key];
+          const typedValue = valueConverter(value, opts);
+          result[typedKey] = typedValue;
+        }
+      }
+      return result;
+    };
+  }
+
+  function createPromiseConverter(converter) {
+    return (V, opts) =>
+      PromisePrototypeThen(PromiseResolve(V), (V) => converter(V, opts));
+  }
+
+  function invokeCallbackFunction(
+    callable,
+    args,
+    thisArg,
+    returnValueConverter,
+    opts,
+  ) {
+    try {
+      const rv = ReflectApply(callable, thisArg, args);
+      return returnValueConverter(rv, {
+        prefix: opts.prefix,
+        context: "return value",
+      });
+    } catch (err) {
+      if (opts.returnsPromise === true) {
+        return PromiseReject(err);
+      }
+      throw err;
+    }
+  }
+
+  const brand = Symbol("[[webidl.brand]]");
+
+  function createInterfaceConverter(name, prototype) {
+    return (V, opts) => {
+      if (!(V instanceof prototype) || V[brand] !== brand) {
+        throw makeException(TypeError, `is not of type ${name}.`, opts);
+      }
+      return V;
+    };
+  }
+
+  // TODO(lucacasonato): have the user pass in the prototype, and not the type.
+  function createBranded(Type) {
+    const t = ObjectCreate(Type.prototype);
+    t[brand] = brand;
+    return t;
+  }
+
+  function assertBranded(self, prototype) {
+    if (!(self instanceof prototype) || self[brand] !== brand) {
+      throw new TypeError("Illegal invocation");
+    }
+  }
+
+  function illegalConstructor() {
+    throw new TypeError("Illegal constructor");
+  }
+
+  function define(target, source) {
+    for (const key of ReflectOwnKeys(source)) {
+      const descriptor = ReflectGetOwnPropertyDescriptor(source, key);
+      if (descriptor && !ReflectDefineProperty(target, key, descriptor)) {
+        throw new TypeError(`Cannot redefine property: ${String(key)}`);
+      }
+    }
+  }
+
+  const _iteratorInternal = Symbol("iterator internal");
+
+  const globalIteratorPrototype = ObjectGetPrototypeOf(ArrayIteratorPrototype);
+
+  function mixinPairIterable(name, prototype, dataSymbol, keyKey, valueKey) {
+    const iteratorPrototype = ObjectCreate(globalIteratorPrototype, {
+      [SymbolToStringTag]: { configurable: true, value: `${name} Iterator` },
+    });
+    define(iteratorPrototype, {
+      next() {
+        const internal = this && this[_iteratorInternal];
+        if (!internal) {
+          throw new TypeError(
+            `next() called on a value that is not a ${name} iterator object`,
+          );
+        }
+        const { target, kind, index } = internal;
+        const values = target[dataSymbol];
+        const len = values.length;
+        if (index >= len) {
+          return { value: undefined, done: true };
+        }
+        const pair = values[index];
+        internal.index = index + 1;
+        let result;
+        switch (kind) {
+          case "key":
+            result = pair[keyKey];
+            break;
+          case "value":
+            result = pair[valueKey];
+            break;
+          case "key+value":
+            result = [pair[keyKey], pair[valueKey]];
+            break;
+        }
+        return { value: result, done: false };
+      },
+    });
+    function createDefaultIterator(target, kind) {
+      const iterator = ObjectCreate(iteratorPrototype);
+      ObjectDefineProperty(iterator, _iteratorInternal, {
+        value: { target, kind, index: 0 },
+        configurable: true,
+      });
+      return iterator;
+    }
+
+    function entries() {
+      assertBranded(this, prototype);
+      return createDefaultIterator(this, "key+value");
+    }
+
+    const properties = {
+      entries: {
+        value: entries,
+        writable: true,
+        enumerable: true,
+        configurable: true,
+      },
+      [SymbolIterator]: {
+        value: entries,
+        writable: true,
+        enumerable: false,
+        configurable: true,
+      },
+      keys: {
+        value: function keys() {
+          assertBranded(this, prototype);
+          return createDefaultIterator(this, "key");
+        },
+        writable: true,
+        enumerable: true,
+        configurable: true,
+      },
+      values: {
+        value: function values() {
+          assertBranded(this, prototype);
+          return createDefaultIterator(this, "value");
+        },
+        writable: true,
+        enumerable: true,
+        configurable: true,
+      },
+      forEach: {
+        value: function forEach(idlCallback, thisArg = undefined) {
+          assertBranded(this, prototype);
+          const prefix = `Failed to execute 'forEach' on '${name}'`;
+          requiredArguments(arguments.length, 1, { prefix });
+          idlCallback = converters["Function"](idlCallback, {
+            prefix,
+            context: "Argument 1",
+          });
+          idlCallback = FunctionPrototypeBind(
+            idlCallback,
+            thisArg ?? globalThis,
+          );
+          const pairs = this[dataSymbol];
+          for (let i = 0; i < pairs.length; i++) {
+            const entry = pairs[i];
+            idlCallback(entry[valueKey], entry[keyKey], this);
+          }
+        },
+        writable: true,
+        enumerable: true,
+        configurable: true,
+      },
+    };
+    return ObjectDefineProperties(prototype.prototype, properties);
+  }
+
+  function configurePrototype(prototype) {
+    const descriptors = ObjectGetOwnPropertyDescriptors(prototype.prototype);
+    for (const key in descriptors) {
+      if (key === "constructor") continue;
+      const descriptor = descriptors[key];
+      if ("value" in descriptor && typeof descriptor.value === "function") {
+        ObjectDefineProperty(prototype.prototype, key, {
+          enumerable: true,
+          writable: true,
+          configurable: true,
+        });
+      } else if ("get" in descriptor) {
+        ObjectDefineProperty(prototype.prototype, key, {
+          enumerable: true,
+          configurable: true,
+        });
+      }
+    }
+  }
+
+  window.__bootstrap ??= {};
+  window.__bootstrap.webidl = {
+    type,
+    makeException,
+    converters,
+    requiredArguments,
+    createDictionaryConverter,
+    createEnumConverter,
+    createNullableConverter,
+    createSequenceConverter,
+    createRecordConverter,
+    createPromiseConverter,
+    invokeCallbackFunction,
+    createInterfaceConverter,
+    brand,
+    createBranded,
+    assertBranded,
+    illegalConstructor,
+    mixinPairIterable,
+    configurePrototype,
+  };
+})(this);
diff --git a/ext/webidl/Cargo.toml b/ext/webidl/Cargo.toml
new file mode 100644
index 000000000..e1dc61feb
--- /dev/null
+++ b/ext/webidl/Cargo.toml
@@ -0,0 +1,17 @@
+# Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
+
+[package]
+name = "deno_webidl"
+version = "0.14.0"
+authors = ["the Deno authors"]
+edition = "2018"
+license = "MIT"
+readme = "README.md"
+repository = "https://github.com/denoland/deno"
+description = "WebIDL implementation for Deno"
+
+[lib]
+path = "lib.rs"
+
+[dependencies]
+deno_core = { version = "0.96.0", path = "../../core" }
diff --git a/ext/webidl/README.md b/ext/webidl/README.md
new file mode 100644
index 000000000..ce2d661e3
--- /dev/null
+++ b/ext/webidl/README.md
@@ -0,0 +1,6 @@
+# deno_webidl
+
+This crate implements WebIDL for Deno. It consists of infrastructure to do ECMA
+-> WebIDL conversions.
+
+Spec: https://heycam.github.io/webidl/
diff --git a/ext/webidl/internal.d.ts b/ext/webidl/internal.d.ts
new file mode 100644
index 000000000..9d151a6d1
--- /dev/null
+++ b/ext/webidl/internal.d.ts
@@ -0,0 +1,341 @@
+// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
+// deno-lint-ignore-file no-explicit-any ban-types
+
+/// <reference no-default-lib="true" />
+/// <reference lib="esnext" />
+
+declare namespace globalThis {
+  declare namespace __bootstrap {
+    declare namespace webidl {
+      declare interface ConverterOpts {
+        /**
+         * The prefix for error messages created by this converter.
+         * Examples:
+         *    - `Failed to construct 'Event'`
+         *    - `Failed to execute 'removeEventListener' on 'EventTarget'`
+         */
+        prefix: string;
+      }
+      declare interface ValueConverterOpts extends ConverterOpts {
+        /**
+         * The context of this value error messages created by this converter.
+         * Examples:
+         *    - `Argument 1`
+         *    - `Argument 3`
+         */
+        context: string;
+      }
+      declare function makeException(
+        ErrorType: any,
+        message: string,
+        opts: ValueConverterOpts,
+      ): any;
+      declare interface IntConverterOpts extends ValueConverterOpts {
+        /**
+         * Wether to throw if the number is outside of the acceptable values for
+         * this type.
+         */
+        enforceRange?: boolean;
+        /**
+         * Wether to clamp this number to the acceptable values for this type.
+         */
+        clamp?: boolean;
+      }
+      declare interface StringConverterOpts extends ValueConverterOpts {
+        /**
+         * Wether to treat `null` value as an empty string.
+         */
+        treatNullAsEmptyString?: boolean;
+      }
+      declare interface BufferConverterOpts extends ValueConverterOpts {
+        /**
+         * Wether to allow `SharedArrayBuffer` (not just `ArrayBuffer`).
+         */
+        allowShared?: boolean;
+      }
+      declare const converters: {
+        any(v: any): any;
+        /**
+         * Convert a value into a `boolean` (bool).
+         */
+        boolean(v: any, opts?: IntConverterOpts): boolean;
+        /**
+         * Convert a value into a `byte` (int8).
+         */
+        byte(v: any, opts?: IntConverterOpts): number;
+        /**
+         * Convert a value into a `octet` (uint8).
+         */
+        octet(v: any, opts?: IntConverterOpts): number;
+        /**
+         * Convert a value into a `short` (int16).
+         */
+        short(v: any, opts?: IntConverterOpts): number;
+        /**
+         * Convert a value into a `unsigned short` (uint16).
+         */
+        ["unsigned short"](v: any, opts?: IntConverterOpts): number;
+        /**
+         * Convert a value into a `long` (int32).
+         */
+        long(v: any, opts?: IntConverterOpts): number;
+        /**
+         * Convert a value into a `unsigned long` (uint32).
+         */
+        ["unsigned long"](v: any, opts?: IntConverterOpts): number;
+        /**
+         * Convert a value into a `long long` (int64).
+         * **Note this is truncated to a JS number (53 bit precision).**
+         */
+        ["long long"](v: any, opts?: IntConverterOpts): number;
+        /**
+         * Convert a value into a `unsigned long long` (uint64).
+         * **Note this is truncated to a JS number (53 bit precision).**
+         */
+        ["unsigned long long"](v: any, opts?: IntConverterOpts): number;
+        /**
+         * Convert a value into a `float` (f32).
+         */
+        float(v: any, opts?: ValueConverterOpts): number;
+        /**
+         * Convert a value into a `unrestricted float` (f32, infinity, or NaN).
+         */
+        ["unrestricted float"](v: any, opts?: ValueConverterOpts): number;
+        /**
+         * Convert a value into a `double` (f64).
+         */
+        double(v: any, opts?: ValueConverterOpts): number;
+        /**
+         * Convert a value into a `unrestricted double` (f64, infinity, or NaN).
+         */
+        ["unrestricted double"](v: any, opts?: ValueConverterOpts): number;
+        /**
+         * Convert a value into a `DOMString` (string).
+         */
+        DOMString(v: any, opts?: StringConverterOpts): string;
+        /**
+         * Convert a value into a `ByteString` (string with only u8 codepoints).
+         */
+        ByteString(v: any, opts?: StringConverterOpts): string;
+        /**
+         * Convert a value into a `USVString` (string with only valid non
+         * surrogate Unicode code points).
+         */
+        USVString(v: any, opts?: StringConverterOpts): string;
+        /**
+         * Convert a value into an `object` (object).
+         */
+        object(v: any, opts?: ValueConverterOpts): object;
+        /**
+         * Convert a value into an `ArrayBuffer` (ArrayBuffer).
+         */
+        ArrayBuffer(v: any, opts?: BufferConverterOpts): ArrayBuffer;
+        /**
+         * Convert a value into a `DataView` (ArrayBuffer).
+         */
+        DataView(v: any, opts?: BufferConverterOpts): DataView;
+        /**
+         * Convert a value into a `Int8Array` (Int8Array).
+         */
+        Int8Array(v: any, opts?: BufferConverterOpts): Int8Array;
+        /**
+         * Convert a value into a `Int16Array` (Int16Array).
+         */
+        Int16Array(v: any, opts?: BufferConverterOpts): Int16Array;
+        /**
+         * Convert a value into a `Int32Array` (Int32Array).
+         */
+        Int32Array(v: any, opts?: BufferConverterOpts): Int32Array;
+        /**
+         * Convert a value into a `Uint8Array` (Uint8Array).
+         */
+        Uint8Array(v: any, opts?: BufferConverterOpts): Uint8Array;
+        /**
+         * Convert a value into a `Uint16Array` (Uint16Array).
+         */
+        Uint16Array(v: any, opts?: BufferConverterOpts): Uint16Array;
+        /**
+         * Convert a value into a `Uint32Array` (Uint32Array).
+         */
+        Uint32Array(v: any, opts?: BufferConverterOpts): Uint32Array;
+        /**
+         * Convert a value into a `Uint8ClampedArray` (Uint8ClampedArray).
+         */
+        Uint8ClampedArray(
+          v: any,
+          opts?: BufferConverterOpts,
+        ): Uint8ClampedArray;
+        /**
+         * Convert a value into a `Float32Array` (Float32Array).
+         */
+        Float32Array(v: any, opts?: BufferConverterOpts): Float32Array;
+        /**
+         * Convert a value into a `Float64Array` (Float64Array).
+         */
+        Float64Array(v: any, opts?: BufferConverterOpts): Float64Array;
+        /**
+         * Convert a value into an `ArrayBufferView` (ArrayBufferView).
+         */
+        ArrayBufferView(v: any, opts?: BufferConverterOpts): ArrayBufferView;
+        /**
+         * Convert a value into a `BufferSource` (ArrayBuffer or ArrayBufferView).
+         */
+        BufferSource(
+          v: any,
+          opts?: BufferConverterOpts,
+        ): ArrayBuffer | ArrayBufferView;
+        /**
+         * Convert a value into a `DOMTimeStamp` (u64). Alias for unsigned long long
+         */
+        DOMTimeStamp(v: any, opts?: IntConverterOpts): number;
+        /**
+         * Convert a value into a `Function` ((...args: any[]) => any).
+         */
+        Function(v: any, opts?: ValueConverterOpts): (...args: any) => any;
+        /**
+         * Convert a value into a `VoidFunction` (() => void).
+         */
+        VoidFunction(v: any, opts?: ValueConverterOpts): () => void;
+        ["UVString?"](v: any, opts?: ValueConverterOpts): string | null;
+        ["sequence<double>"](v: any, opts?: ValueConverterOpts): number[];
+
+        [type: string]: (v: any, opts: ValueConverterOpts) => any;
+      };
+
+      /**
+       * Assert that the a function has at least a required amount of arguments.
+       */
+      declare function requiredArguments(
+        length: number,
+        required: number,
+        opts: ConverterOpts,
+      ): void;
+      declare type Dictionary = DictionaryMember[];
+      declare interface DictionaryMember {
+        key: string;
+        converter: (v: any, opts: ValueConverterOpts) => any;
+        defaultValue?: any;
+        required?: boolean;
+      }
+
+      /**
+       * Create a converter for dictionaries.
+       */
+      declare function createDictionaryConverter<T>(
+        name: string,
+        ...dictionaries: Dictionary[]
+      ): (v: any, opts: ValueConverterOpts) => T;
+
+      /**
+       * Create a converter for enums.
+       */
+      declare function createEnumConverter(
+        name: string,
+        values: string[],
+      ): (v: any, opts: ValueConverterOpts) => string;
+
+      /**
+       * Create a converter that makes the contained type nullable.
+       */
+      declare function createNullableConverter<T>(
+        converter: (v: any, opts: ValueConverterOpts) => T,
+      ): (v: any, opts: ValueConverterOpts) => T | null;
+
+      /**
+       * Create a converter that converts a sequence of the inner type.
+       */
+      declare function createSequenceConverter<T>(
+        converter: (v: any, opts: ValueConverterOpts) => T,
+      ): (v: any, opts: ValueConverterOpts) => T[];
+
+      /**
+       * Create a converter that converts a Promise of the inner type.
+       */
+      declare function createPromiseConverter<T>(
+        converter: (v: any, opts: ValueConverterOpts) => T,
+      ): (v: any, opts: ValueConverterOpts) => Promise<T>;
+
+      /**
+       * Invoke a callback function.
+       */
+      declare function invokeCallbackFunction<T>(
+        callable: (...args: any) => any,
+        args: any[],
+        thisArg: any,
+        returnValueConverter: (v: any, opts: ValueConverterOpts) => T,
+        opts: ConverterOpts & { returnsPromise?: boolean },
+      ): T;
+
+      /**
+       * Throw an illegal constructor error.
+       */
+      declare function illegalConstructor(): never;
+
+      /**
+       * The branding symbol.
+       */
+      declare const brand: unique symbol;
+
+      /**
+       * Create a branded instance of an interface.
+       */
+      declare function createBranded(self: any): any;
+
+      /**
+       * Assert that self is branded.
+       */
+      declare function assertBranded(self: any, type: any): void;
+
+      /**
+       * Create a converter for interfaces.
+       */
+      declare function createInterfaceConverter(
+        name: string,
+        prototype: any,
+      ): (v: any, opts: ValueConverterOpts) => any;
+
+      declare function createRecordConverter<
+        K extends string | number | symbol,
+        V,
+      >(
+        keyConverter: (v: any, opts: ValueConverterOpts) => K,
+        valueConverter: (v: any, opts: ValueConverterOpts) => V,
+      ): (
+        v: Record<K, V>,
+        opts: ValueConverterOpts,
+      ) => any;
+
+      /**
+       * Mix in the iterable declarations defined in WebIDL.
+       * https://heycam.github.io/webidl/#es-iterable
+       */
+      declare function mixinPairIterable(
+        name: string,
+        prototype: any,
+        dataSymbol: symbol,
+        keyKey: string | number | symbol,
+        valueKey: string | number | symbol,
+      ): void;
+
+      /**
+       * Configure prototype properties enumerability / writability / configurability.
+       */
+      declare function configurePrototype(prototype: any);
+
+      /**
+       * Get the WebIDL / ES type of a value.
+       */
+      declare function type(
+        v: any,
+      ):
+        | "Null"
+        | "Undefined"
+        | "Boolean"
+        | "Number"
+        | "String"
+        | "Symbol"
+        | "BigInt"
+        | "Object";
+    }
+  }
+}
diff --git a/ext/webidl/lib.rs b/ext/webidl/lib.rs
new file mode 100644
index 000000000..6dda68442
--- /dev/null
+++ b/ext/webidl/lib.rs
@@ -0,0 +1,14 @@
+// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
+
+use deno_core::include_js_files;
+use deno_core::Extension;
+
+/// Load and execute the javascript code.
+pub fn init() -> Extension {
+  Extension::builder()
+    .js(include_js_files!(
+      prefix "deno:ext/webidl",
+      "00_webidl.js",
+    ))
+    .build()
+}