Add support for async/await using Babel

.eslintrc

@@ -1,6 +1,6 @@
 {
   "parserOptions": {
-    "ecmaVersion": 6,
+    "ecmaVersion": 8,
     "sourceType": "module",
   },
 

external/builder/preprocessor2.js

@@ -288,6 +288,7 @@ function preprocessPDFJSCode(ctx, code) {
     },
   };
   var parseOptions = {
+    ecmaVersion: 8,
     locations: true,
     sourceFile: ctx.sourceFile,
     sourceType: 'module',

gulpfile.js

@@ -177,7 +177,14 @@ function createWebpackConfig(defines, output) {
           exclude: /src[\\\/]core[\\\/](glyphlist|unicode)/,
           options: {
             presets: skipBabel ? undefined : ['env'],
-            plugins: ['transform-es2015-modules-commonjs'],
+            plugins: [
+              'transform-es2015-modules-commonjs',
+              ['transform-runtime', {
+                'helpers': false,
+                'polyfill': false,
+                'regenerator': true,
+              }],
+            ],
           },
         },
         {
@@ -808,7 +815,7 @@ gulp.task('mozcentral', ['mozcentral-pre']);
 gulp.task('chromium-pre', ['buildnumber', 'locale'], function () {
   console.log();
   console.log('### Building Chromium extension');
-  var defines = builder.merge(DEFINES, { CHROME: true, SKIP_BABEL: true, });
+  var defines = builder.merge(DEFINES, { CHROME: true, });
 
   var CHROME_BUILD_DIR = BUILD_DIR + '/chromium/',
       CHROME_BUILD_CONTENT_DIR = CHROME_BUILD_DIR + '/content/';
@@ -897,6 +904,11 @@ gulp.task('lib', ['buildnumber'], function () {
       presets: noPreset ? undefined : ['env'],
       plugins: [
         'transform-es2015-modules-commonjs',
+        ['transform-runtime', {
+          'helpers': false,
+          'polyfill': false,
+          'regenerator': true,
+        }],
         babelPluginReplaceNonWebPackRequire,
       ],
     }).code;

package.json

@@ -7,6 +7,7 @@
     "babel-core": "^6.26.3",
     "babel-loader": "^7.1.5",
     "babel-plugin-transform-es2015-modules-commonjs": "^6.26.2",
+    "babel-plugin-transform-runtime": "^6.23.0",
     "babel-preset-env": "^1.7.0",
     "core-js": "^2.5.7",
     "escodegen": "^1.11.0",

src/core/evaluator.js

@@ -131,19 +131,17 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
     this.options = options || DefaultPartialEvaluatorOptions;
     this.pdfFunctionFactory = pdfFunctionFactory;
 
-    this.fetchBuiltInCMap = (name) => {
+    this.fetchBuiltInCMap = async (name) => {
       if (this.builtInCMapCache.has(name)) {
-        return Promise.resolve(this.builtInCMapCache.get(name));
+        return this.builtInCMapCache.get(name);
       }
-      return this.handler.sendWithPromise('FetchBuiltInCMap', {
-        name,
-      }).then((data) => {
+      const data = await this.handler.sendWithPromise('FetchBuiltInCMap',
+                                                      { name, });
       if (data.compressionType !== CMapCompressionType.NONE) {
         // Given the size of uncompressed CMaps, only cache compressed ones.
         this.builtInCMapCache.set(name, data);
       }
       return data;
-      });
     };
   }
 

src/core/obj.js

@@ -1497,29 +1497,23 @@ var XRef = (function XRefClosure() {
       return xrefEntry;
     },
 
-    fetchIfRefAsync: function XRef_fetchIfRefAsync(obj, suppressEncryption) {
+    async fetchIfRefAsync(obj, suppressEncryption) {
       if (!isRef(obj)) {
-        return Promise.resolve(obj);
+        return obj;
       }
       return this.fetchAsync(obj, suppressEncryption);
     },
 
-    fetchAsync: function XRef_fetchAsync(ref, suppressEncryption) {
-      var streamManager = this.stream.manager;
-      var xref = this;
-      return new Promise(function tryFetch(resolve, reject) {
+    async fetchAsync(ref, suppressEncryption) {
       try {
-          resolve(xref.fetch(ref, suppressEncryption));
-        } catch (e) {
-          if (e instanceof MissingDataException) {
-            streamManager.requestRange(e.begin, e.end).then(function () {
-              tryFetch(resolve, reject);
-            }, reject);
-            return;
+        return this.fetch(ref, suppressEncryption);
+      } catch (ex) {
+        if (!(ex instanceof MissingDataException)) {
+          throw ex;
         }
-          reject(e);
+        await this.pdfManager.requestRange(ex.begin, ex.end);
+        return this.fetchAsync(ref, suppressEncryption);
       }
-      });
     },
 
     getCatalogObj: function XRef_getCatalogObj() {

src/core/pdf_manager.js

@@ -72,7 +72,7 @@ class BasePdfManager {
     return this.pdfDocument.cleanup();
   }
 
-  ensure(obj, prop, args) {
+  async ensure(obj, prop, args) {
     unreachable('Abstract method `ensure` called');
   }
 
@@ -111,15 +111,12 @@ class LocalPdfManager extends BasePdfManager {
     this._loadedStreamPromise = Promise.resolve(stream);
   }
 
-  ensure(obj, prop, args) {
-    return new Promise(function(resolve) {
+  async ensure(obj, prop, args) {
     const value = obj[prop];
     if (typeof value === 'function') {
-        resolve(value.apply(obj, args));
-      } else {
-        resolve(value);
+      return value.apply(obj, args);
     }
-    });
+    return value;
   }
 
   requestRange(begin, end) {
@@ -155,30 +152,20 @@ class NetworkPdfManager extends BasePdfManager {
     this.pdfDocument = new PDFDocument(this, this.streamManager.getStream());
   }
 
-  ensure(obj, prop, args) {
-    return new Promise((resolve, reject) => {
-      let ensureHelper = () => {
+  async ensure(obj, prop, args) {
     try {
       const value = obj[prop];
-          let result;
       if (typeof value === 'function') {
-            result = value.apply(obj, args);
-          } else {
-            result = value;
+        return value.apply(obj, args);
       }
-          resolve(result);
+      return value;
     } catch (ex) {
       if (!(ex instanceof MissingDataException)) {
-            reject(ex);
-            return;
+        throw ex;
       }
-          this.streamManager.requestRange(ex.begin, ex.end)
-            .then(ensureHelper, reject);
+      await this.requestRange(ex.begin, ex.end);
+      return this.ensure(obj, prop, args);
     }
-      };
-
-      ensureHelper();
-    });
   }
 
   requestRange(begin, end) {

src/display/fetch_stream.js

@@ -152,11 +152,11 @@ class PDFFetchStreamReader {
     return this._isStreamingSupported;
   }
 
-  read() {
-    return this._headersCapability.promise.then(() => {
-      return this._reader.read().then(({ value, done, }) => {
+  async read() {
+    await this._headersCapability.promise;
+    const { value, done, } = await this._reader.read();
     if (done) {
-          return Promise.resolve({ value, done, });
+      return { value, done, };
     }
     this._loaded += value.byteLength;
     if (this.onProgress) {
@@ -166,9 +166,7 @@ class PDFFetchStreamReader {
       });
     }
     let buffer = new Uint8Array(value).buffer;
-        return Promise.resolve({ value: buffer, done: false, });
-      });
-    });
+    return { value: buffer, done: false, };
   }
 
   cancel(reason) {
@@ -223,20 +221,18 @@ class PDFFetchStreamRangeReader {
     return this._isStreamingSupported;
   }
 
-  read() {
-    return this._readCapability.promise.then(() => {
-      return this._reader.read().then(({ value, done, }) => {
+  async read() {
+    await this._readCapability.promise;
+    const { value, done, } = await this._reader.read();
     if (done) {
-          return Promise.resolve({ value, done, });
+      return { value, done, };
     }
     this._loaded += value.byteLength;
     if (this.onProgress) {
       this.onProgress({ loaded: this._loaded, });
     }
     let buffer = new Uint8Array(value).buffer;
-        return Promise.resolve({ value: buffer, done: false, });
-      });
-    });
+    return { value: buffer, done: false, };
   }
 
   cancel(reason) {