Refactor snapshot build (#2825)

Instead of using core/snapshot_creator.rs, instead two crates are
introduced which allow building the snapshot during build.rs.

Rollup is removed and replaced with our own bundler. This removes
the Node build dependency. Modules in //js now use Deno-style imports
with file extensions, rather than Node style extensionless imports.

This improves incremental build time when changes are made to //js files
by about 40 seconds.

1 files changed, 17 insertions, 12 deletions

diff --git a/js/fetch.ts b/js/fetch.ts
index 2e18ece9a..d66eb1c48 100644
--- a/js/fetch.ts
+++ b/js/fetch.ts
@@ -1,16 +1,21 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
-import { assert, createResolvable, notImplemented, isTypedArray } from "./util";
-import * as domTypes from "./dom_types";
-import { TextDecoder, TextEncoder } from "./text_encoding";
-import { DenoBlob, bytesSymbol as blobBytesSymbol } from "./blob";
-import { Headers } from "./headers";
-import * as io from "./io";
-import { read, close } from "./files";
-import { Buffer } from "./buffer";
-import { FormData } from "./form_data";
-import { URLSearchParams } from "./url_search_params";
-import * as dispatch from "./dispatch";
-import { sendAsync } from "./dispatch_json";
+import {
+  assert,
+  createResolvable,
+  notImplemented,
+  isTypedArray
+} from "./util.ts";
+import * as domTypes from "./dom_types.ts";
+import { TextDecoder, TextEncoder } from "./text_encoding.ts";
+import { DenoBlob, bytesSymbol as blobBytesSymbol } from "./blob.ts";
+import { Headers } from "./headers.ts";
+import * as io from "./io.ts";
+import { read, close } from "./files.ts";
+import { Buffer } from "./buffer.ts";
+import { FormData } from "./form_data.ts";
+import { URLSearchParams } from "./url_search_params.ts";
+import * as dispatch from "./dispatch.ts";
+import { sendAsync } from "./dispatch_json.ts";
 
 function getHeaderValueParams(value: string): Map<string, string> {
   const params = new Map();