Support async/await in the dart2js frontend.

sdk/lib/_internal/compiler/implementation/dart2js.dart

 // Copyright (c) 2013, 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.
 
 library dart2js.cmdline;
 
 import 'dart:async'
     show Future, EventSink;
 import 'dart:convert' show UTF8, LineSplitter;
 import 'dart:io'
@@ skipping 96 matching lines @@
   Uri sourceMapOut = currentDirectory.resolve('out.js.map');
   Uri packageRoot = null;
   List<String> options = new List<String>();
   bool explicitOut = false;
   bool wantHelp = false;
   bool wantVersion = false;
   String outputLanguage = 'JavaScript';
   bool stripArgumentSet = false;
   bool analyzeOnly = false;
   bool analyzeAll = false;
+  bool enableAsyncAwait = false;
   bool trustTypeAnnotations = false;
   bool checkedMode = false;
   // List of provided options that imply that output is expected.
   List<String> optionsImplyCompilation = <String>[];
   bool hasDisallowUnsafeEval = false;
   // TODO(johnniwinther): Measure time for reading files.
   SourceFileProvider inputProvider = new CompilerSourceFileProvider();
   diagnosticHandler = new FormattingDiagnosticHandler(inputProvider);
   Map<String, dynamic> environment = new Map<String, dynamic>();
 
@@ skipping 55 matching lines @@
   setAnalyzeOnly(String argument) {
     analyzeOnly = true;
     passThrough(argument);
   }
 
   setAnalyzeAll(String argument) {
     analyzeAll = true;
     passThrough(argument);
   }
 
+  setEnableAsync(String argument) {
+    enableAsyncAwait = true;
+    passThrough(argument);
+  }
+
   setVerbose(_) {
     diagnosticHandler.verbose = true;
     passThrough('--verbose');
   }
 
   implyCompilation(String argument) {
     optionsImplyCompilation.add(argument);
     passThrough(argument);
   }
 
@@ skipping 108 matching lines @@
     new OptionHandler('--analyze-signatures-only', setAnalyzeOnly),
     new OptionHandler('--disable-native-live-type-analysis', passThrough),
     new OptionHandler('--categories=.*', setCategories),
     new OptionHandler('--disable-type-inference', implyCompilation),
     new OptionHandler('--terse', passThrough),
     new OptionHandler('--dump-info', implyCompilation),
     new OptionHandler('--disallow-unsafe-eval',
                       (_) => hasDisallowUnsafeEval = true),
     new OptionHandler('--show-package-warnings', passThrough),
     new OptionHandler('--csp', passThrough),
+    new OptionHandler('--enable-async', setEnableAsync),
     new OptionHandler('-D.+=.*', addInEnvironment),
 
     // The following two options must come last.
     new OptionHandler('-.*', (String argument) {
       helpAndFail("Unknown option '$argument'.");
     }),
     new OptionHandler('.*', (String argument) {
       arguments.add(nativeToUriPath(argument));
     })
   ];
@@ skipping 40 matching lines @@
       diagnosticHandler.info(
           "Option '--analyze-all' implies '--analyze-only'.",
           api.Diagnostic.INFO);
     }
     diagnosticHandler.info(
         "Options $optionsImplyCompilation indicate that output is expected, "
         "but compilation is turned off by the option '--analyze-only'.",
         api.Diagnostic.INFO);
   }
   if (analyzeAll) analyzeOnly = true;
+  if (enableAsyncAwait && !analyzeOnly) {
+    helpAndFail("Option '--enable-async' currently only supported together "

[floitsch, 2014/11/03 17:55:54]

... is currently ...

... in combination with ... ?

[Johnni Winther, 2014/11/04 12:24:33]

Done.

+                "with the '--analyze-only' option.");
+  }
 
   diagnosticHandler.info('Package root is $packageRoot');
 
   options.add('--out=$out');
   options.add('--source-map=$sourceMapOut');
 
   RandomAccessFileOutputProvider outputProvider =
       new RandomAccessFileOutputProvider(
           out, sourceMapOut, onInfo: diagnosticHandler.info, onFailure: fail);
 
@@ skipping 278 matching lines @@
       } else if (exitCode == 253) {
         print(">>> TEST CRASH");
       } else {
         print(">>> TEST FAIL");
       }
       stderr.writeln(">>> EOF STDERR");
       subscription.resume();
     });
   });
 }