Support async/await in the dart2js frontend.

sdk/lib/_internal/compiler/implementation/compiler.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart2js;
 
 /**
  * If true, print a warning for each method that was resolved, but not
  * compiled.
  */
@@ skipping 700 matching lines @@
   /// `true` if the last diagnostic was filtered, in which case the
   /// accompanying info message should be filtered as well.
   bool lastDiagnosticWasFiltered = false;
 
   /// Map containing information about the warnings and hints that have been
   /// suppressed for each library.
   Map<Uri, SuppressionInfo> suppressedWarnings = <Uri, SuppressionInfo>{};
 
   final bool suppressWarnings;
 
+  /// `true` if async/await features are supported.
+  final bool enableAsyncAwait;
+
   /// If `true`, some values are cached for reuse in incremental compilation.
   /// Incremental compilation is basically calling [run] more than once.
   final bool hasIncrementalSupport;
 
   api.CompilerOutputProvider outputProvider;
 
   bool disableInlining = false;
 
   /// True if compilation was aborted with a [CompilerCancelledException]. Only
   /// set after Future retuned by [run] has completed.
@@ skipping 23 matching lines @@
   ClassElement doubleClass;
   ClassElement stringClass;
   ClassElement functionClass;
   ClassElement nullClass;
   ClassElement listClass;
   ClassElement typeClass;
   ClassElement mapClass;
   ClassElement symbolClass;
   ClassElement stackTraceClass;
   ClassElement typedDataClass;
+  ClassElement futureClass;
+  ClassElement iterableClass;
+  ClassElement streamClass;
 
   /// The constant for the [proxy] variable defined in dart:core.
   ConstantValue proxyConstant;
 
   // TODO(johnniwinther): Move this to the JavaScriptBackend.
   /// The constant for the [patch] variable defined in dart:_js_helper.
   ConstantValue patchConstant;
 
   // TODO(johnniwinther): Move this to the JavaScriptBackend.
   ClassElement nativeAnnotationClass;
@@ skipping 177 matching lines @@
             this.verbose: false,
             this.sourceMapUri: null,
             this.outputUri: null,
             this.buildId: UNDETERMINED_BUILD_ID,
             this.terseDiagnostics: false,
             this.dumpInfo: false,
             this.showPackageWarnings: false,
             this.useContentSecurityPolicy: false,
             this.suppressWarnings: false,
             bool hasIncrementalSupport: false,
+            this.enableAsyncAwait: false,
             api.CompilerOutputProvider outputProvider,
             List<String> strips: const []})
       : this.disableTypeInferenceFlag =
           disableTypeInferenceFlag || !emitJavaScript,
         this.analyzeOnly =
             analyzeOnly || analyzeSignaturesOnly || analyzeAllFlag,
         this.analyzeSignaturesOnly = analyzeSignaturesOnly,
         this.analyzeAllFlag = analyzeAllFlag,
         this.hasIncrementalSupport = hasIncrementalSupport,
         cacheStrategy = new CacheStrategy(hasIncrementalSupport),
@@ skipping 97 matching lines @@
     if (node == CURRENT_ELEMENT_SPANNABLE) {
       node = currentElement;
     } else if (node == NO_LOCATION_SPANNABLE) {
       if (currentElement == null) return null;
       node = currentElement;
     }
     if (node is SourceSpan) {
       return node;
     } else if (node is Node) {
       return spanFromNode(node);
+    } else if (node is TokenPair) {
+      return spanFromTokens(node.begin, node.end);
     } else if (node is Token) {
       return spanFromTokens(node, node);
     } else if (node is HInstruction) {
       return spanFromHInstruction(node);
     } else if (node is Element) {
       return spanFromElement(node);
     } else if (node is MetadataAnnotation) {
       Uri uri = node.annotatedElement.compilationUnit.script.readableUri;
       return spanFromTokens(node.beginToken, node.endToken, uri);
     } else if (node is Local) {
@@ skipping 95 matching lines @@
     if (uri == DART_CORE) {
       initializeCoreClasses();
       identicalFunction = coreLibrary.find('identical');
     } else if (uri == DART_INTERNAL) {
       symbolImplementationClass = findRequiredElement(library, 'Symbol');
     } else if (uri == DART_MIRRORS) {
       mirrorSystemClass = findRequiredElement(library, 'MirrorSystem');
       mirrorsUsedClass = findRequiredElement(library, 'MirrorsUsed');
     } else if (uri == DART_ASYNC) {
       deferredLibraryClass = findRequiredElement(library, 'DeferredLibrary');
+      futureClass = findRequiredElement(library, 'Future');
+      streamClass = findRequiredElement(library, 'Stream');
     } else if (uri == DART_NATIVE_TYPED_DATA) {
       typedDataClass = findRequiredElement(library, 'NativeTypedData');
     } else if (uri == js_backend.JavaScriptBackend.DART_JS_HELPER) {
       nativeAnnotationClass = findRequiredElement(library, 'Native');
     }
     return backend.onLibraryScanned(library, loader);
   }
 
   /// This method is called when all new libraries loaded through
   /// [LibraryLoader.loadLibrary] has been loaded and their imports/exports
@@ skipping 76 matching lines @@
     numClass = lookupCoreClass('num');
     intClass = lookupCoreClass('int');
     doubleClass = lookupCoreClass('double');
     stringClass = lookupCoreClass('String');
     functionClass = lookupCoreClass('Function');
     listClass = lookupCoreClass('List');
     typeClass = lookupCoreClass('Type');
     mapClass = lookupCoreClass('Map');
     nullClass = lookupCoreClass('Null');
     stackTraceClass = lookupCoreClass('StackTrace');
+    iterableClass = lookupCoreClass('Iterable');
     symbolClass = lookupCoreClass('Symbol');
     if (!missingCoreClasses.isEmpty) {
       internalError(coreLibrary,
           'dart:core library does not contain required classes: '
           '$missingCoreClasses');
     }
   }
 
   Element _unnamedListConstructor;
   Element get unnamedListConstructor {
@@ skipping 864 matching lines @@
   int warnings = 0;
   int hints = 0;
 }
 
 class GenericTask extends CompilerTask {
   final String name;
 
   GenericTask(this.name, Compiler compiler)
       : super(compiler);
 }