Merge pull request #10470 from Snuffleupagus/mozcentral-streams

Try to, completely, avoid loading the `ReadableStream` polyfill in MOZCENTRAL builds

extensions/firefox/content/streams_polyfill.js

@@ -0,0 +1,19 @@
+/* Copyright 2018 Mozilla Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+if (typeof ReadableStream === "undefined") {
+  require("../../../src/shared/global_scope").ReadableStream =
+    require("../../../external/streams/streams-lib").ReadableStream;
+}

gulpfile.js

@@ -766,6 +766,16 @@ function preprocessDefaultPreferences(content) {
           content + '\n');
 }
 
+function createMozcentralStreamsPolyfillBundle(defines) {
+  var streamsPolyfillOutputName = 'streams_polyfill.js';
+
+  var streamsPolyfillFileConfig = createWebpackConfig(defines, {
+    filename: streamsPolyfillOutputName,
+  });
+  return gulp.src('./extensions/firefox/content/streams_polyfill.js')
+             .pipe(webpack2Stream(streamsPolyfillFileConfig));
+}
+
 gulp.task('mozcentral-pre', gulp.series('buildnumber', 'locale', function () {
   console.log();
   console.log('### Building mozilla-central extension');
@@ -787,6 +797,8 @@ gulp.task('mozcentral-pre', gulp.series('buildnumber', 'locale', function () {
   return merge([
     createBundle(defines).pipe(gulp.dest(MOZCENTRAL_CONTENT_DIR + 'build')),
     createWebBundle(defines).pipe(gulp.dest(MOZCENTRAL_CONTENT_DIR + 'web')),
+    createMozcentralStreamsPolyfillBundle(defines)
+        .pipe(gulp.dest(MOZCENTRAL_CONTENT_DIR + 'build')),
     gulp.src(COMMON_WEB_FILES, { base: 'web/', })
         .pipe(gulp.dest(MOZCENTRAL_CONTENT_DIR + 'web')),
     gulp.src(['external/bcmaps/*.bcmap', 'external/bcmaps/LICENSE'],

src/pdf.worker.js

@@ -12,13 +12,17 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-/* eslint-disable no-unused-vars */
+/* eslint-disable no-restricted-globals, no-unused-vars */
 
 'use strict';
 
-var pdfjsVersion = PDFJSDev.eval('BUNDLE_VERSION');
+if (PDFJSDev.test('MOZCENTRAL') && typeof ReadableStream === 'undefined') {
-var pdfjsBuild = PDFJSDev.eval('BUNDLE_BUILD');
+  importScripts('./streams_polyfill.js');
+}
 
-var pdfjsCoreWorker = require('./core/worker.js');
+const pdfjsVersion = PDFJSDev.eval('BUNDLE_VERSION');
+const pdfjsBuild = PDFJSDev.eval('BUNDLE_BUILD');
+
+const pdfjsCoreWorker = require('./core/worker.js');
 
 exports.WorkerMessageHandler = pdfjsCoreWorker.WorkerMessageHandler;

src/shared/streams_polyfill.js

@@ -14,8 +14,15 @@
  */
 /* eslint-disable no-restricted-globals */
 
-let isReadableStreamSupported = false;
+if (typeof PDFJSDev !== 'undefined' && PDFJSDev.test('MOZCENTRAL')) {
-if (typeof ReadableStream !== 'undefined') {
+  // On the main-thread the `streams_polyfill.js` file is loaded using a
+  // <script> tag; see `web/viewer-snippet-firefox-extension.html`.
+  // On the worker-thread the `streams_polyfill.js` file is (conditionally)
+  // loaded using `importScripts`; see `src/pdf.worker.js`.
+  exports.ReadableStream = ReadableStream;
+} else {
+  let isReadableStreamSupported = false;
+  if (typeof ReadableStream !== 'undefined') {
     // MS Edge may say it has ReadableStream but they are not up to spec yet.
     try {
       // eslint-disable-next-line no-new
@@ -28,11 +35,11 @@ if (typeof ReadableStream !== 'undefined') {
     } catch (e) {
       // The ReadableStream constructor cannot be used.
     }
-}
+  }
-if (isReadableStreamSupported) {
+  if (isReadableStreamSupported) {
     exports.ReadableStream = ReadableStream;
-} else {
+  } else if (typeof PDFJSDev !== 'undefined' &&
-  if (typeof PDFJSDev !== 'undefined' && PDFJSDev.test('IMAGE_DECODERS')) {
+             PDFJSDev.test('IMAGE_DECODERS')) {
     class DummyReadableStream {
       constructor() {
         throw new Error('The current image decoders are synchronous, ' +

src/shared/url_polyfill.js

@@ -32,8 +32,8 @@ if (typeof PDFJSDev !== 'undefined' && !PDFJSDev.test('GENERIC')) {
 
   if (isURLSupported) {
     exports.URL = URL;
-  } else {
+  } else if (typeof PDFJSDev !== 'undefined' &&
-    if (typeof PDFJSDev !== 'undefined' && PDFJSDev.test('IMAGE_DECODERS')) {
+             PDFJSDev.test('IMAGE_DECODERS')) {
     class DummyURL {
       constructor() {
         throw new Error('The current image decoders doesn\'t utilize the ' +
@@ -59,5 +59,4 @@ if (typeof PDFJSDev !== 'undefined' && !PDFJSDev.test('GENERIC')) {
     }
     exports.URL = PolyfillURL;
   }
-  }
 }

web/viewer-snippet-firefox-extension.html

@@ -1,3 +1,10 @@
 <!-- This snippet is used in the Firefox extension (included from viewer.html) -->
 <base href="resource://pdf.js/web/">
+<script>
+  (function() {
+    if (typeof ReadableStream === "undefined") {
+      document.write("<script src=\"../build/streams_polyfill.js\"><\/script>");
+    }
+  })();
+</script>
 <script src="../build/pdf.js"></script>