refactor(web): use encoding_rs for text encoding (#10844)

This commit removes all JS based text encoding / text decoding. Instead
encoding now happens in Rust via encoding_rs (already in tree). This
implementation retains stream support, but adds the last missing
encodings. We are incredibly close to 100% WPT on text encoding now.

This should reduce our baseline heap by quite a bit.

2 files changed, 11 insertions, 17 deletions

diff --git a/extensions/fetch/21_formdata.js b/extensions/fetch/21_formdata.js
index 7b519ddc2..a178025b7 100644
--- a/extensions/fetch/21_formdata.js
+++ b/extensions/fetch/21_formdata.js
@@ -11,7 +11,8 @@
 /// <reference lib="esnext" />
 "use strict";
 
-((_window) => {
+((window) => {
+  const core = window.Deno.core;
   const webidl = globalThis.__bootstrap.webidl;
   const { Blob, File, _byteSequence } = globalThis.__bootstrap.file;
 
@@ -240,8 +241,6 @@
 
   webidl.mixinPairIterable("FormData", FormData, entryList, "name", "value");
 
-  const encoder = new TextEncoder();
-
   class MultipartBuilder {
     /**
      * @param {FormData} formData
@@ -270,7 +269,7 @@
         } else this.#writeField(name, value);
       }
 
-      this.chunks.push(encoder.encode(`\r\n--${this.boundary}--`));
+      this.chunks.push(core.encode(`\r\n--${this.boundary}--`));
 
       let totalLength = 0;
       for (const chunk of this.chunks) {
@@ -309,7 +308,7 @@
       }
       buf += `\r\n`;
 
-      this.chunks.push(encoder.encode(buf));
+      this.chunks.push(core.encode(buf));
     }
 
     /**
@@ -356,7 +355,7 @@
      */
     #writeField(field, value) {
       this.#writeFieldHeaders(field);
-      this.chunks.push(encoder.encode(this.#normalizeNewlines(value)));
+      this.chunks.push(core.encode(this.#normalizeNewlines(value)));
     }
 
     /**
@@ -428,7 +427,6 @@
 
   const LF = "\n".codePointAt(0);
   const CR = "\r".codePointAt(0);
-  const decoder = new TextDecoder("utf-8");
 
   class MultipartParser {
     /**
@@ -442,7 +440,7 @@
 
       this.boundary = `--${boundary}`;
       this.body = body;
-      this.boundaryChars = encoder.encode(this.boundary);
+      this.boundaryChars = core.encode(this.boundary);
     }
 
     /**
@@ -539,7 +537,7 @@
               });
               formData.append(name, blob, filename);
             } else {
-              formData.append(name, decoder.decode(content));
+              formData.append(name, core.decode(content));
             }
           }
         } else if (state === 5 && isNewLine) {
diff --git a/extensions/fetch/22_body.js b/extensions/fetch/22_body.js
index 8c93e0fcf..f0c7ac8bd 100644
--- a/extensions/fetch/22_body.js
+++ b/extensions/fetch/22_body.js
@@ -223,8 +223,6 @@
     return Object.defineProperties(prototype.prototype, mixin);
   }
 
-  const decoder = new TextDecoder();
-
   /**
    * https://fetch.spec.whatwg.org/#concept-body-package-data
    * @param {Uint8Array} bytes
@@ -263,14 +261,12 @@
         throw new TypeError("Missing content type");
       }
       case "JSON":
-        return JSON.parse(decoder.decode(bytes));
+        return JSON.parse(core.decode(bytes));
       case "text":
-        return decoder.decode(bytes);
+        return core.decode(bytes);
     }
   }
 
-  const encoder = new TextEncoder();
-
   /**
    * @param {BodyInit} object
    * @returns {{body: InnerBody, contentType: string | null}}
@@ -305,10 +301,10 @@
       length = res.body.byteLength;
       contentType = res.contentType;
     } else if (object instanceof URLSearchParams) {
-      source = encoder.encode(object.toString());
+      source = core.encode(object.toString());
       contentType = "application/x-www-form-urlencoded;charset=UTF-8";
     } else if (typeof object === "string") {
-      source = encoder.encode(object);
+      source = core.encode(object);
       contentType = "text/plain;charset=UTF-8";
     } else if (object instanceof ReadableStream) {
       stream = object;