Add --no-source-maps flag to dart2js executable

pkg/compiler/lib/src/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 310 matching lines @@
     new OptionHandler('--trust-type-annotations',
                       (_) => setTrustTypeAnnotations(
                           '--trust-type-annotations')),
     new OptionHandler('--trust-primitives',
                       (_) => setTrustPrimitives(
                           '--trust-primitives')),
     new OptionHandler(r'--help|/\?|/h', (_) => wantHelp = true),
     new OptionHandler('--package-root=.+|-p.+', setPackageRoot),
     new OptionHandler('--analyze-all', setAnalyzeAll),
     new OptionHandler('--analyze-only', setAnalyzeOnly),
+    new OptionHandler('--no-source-maps', passThrough),
     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('--deferred-map=.+', implyCompilation),
     new OptionHandler('--dump-info', setDumpInfo),
     new OptionHandler('--disallow-unsafe-eval',
                       (_) => hasDisallowUnsafeEval = true),
     new OptionHandler('--show-package-warnings', passThrough),
@@ skipping 234 matching lines @@
     Show warnings and hints generated from packages.
 
   --preserve-uris
     Preserve the source URIs in the reflection data. Without this flag the
     `uri` getter for `LibraryMirror`s is mangled in minified mode.
 
   --csp
     Disables dynamic generation of code in the generated output. This is
     necessary to satisfy CSP restrictions (see http://www.w3.org/TR/CSP/).
 
+  --no-source-maps
+    Do not generate a source map file.
+
 The following options are only used for compiler development and may
 be removed in a future version:
 
   --output-type=dart
     Output Dart code instead of JavaScript.
 
   --throw-on-error
     Throw an exception if a compile-time error is detected.
 
   --library-root=<directory>
@@ skipping 134 matching lines @@
       } else if (exitCode == 253) {
         print(">>> TEST CRASH");
       } else {
         print(">>> TEST FAIL");
       }
       stderr.writeln(">>> EOF STDERR");
       subscription.resume();
     });
   });
 }