Add --hide-package-warnings option.

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:io'
     show exit, File, FileMode, Platform, RandomAccessFile, FileSystemException;
@@ skipping 261 matching lines @@
     new OptionHandler('--analyze-all', passThrough),
     new OptionHandler('--analyze-only', setAnalyzeOnly),
     new OptionHandler('--analyze-signatures-only', passThrough),
     new OptionHandler('--disable-native-live-type-analysis', passThrough),
     new OptionHandler('--categories=.*', setCategories),
     new OptionHandler('--disable-type-inference', passThrough),
     new OptionHandler('--terse', passThrough),
     new OptionHandler('--dump-info', passThrough),
     new OptionHandler('--disallow-unsafe-eval',
                       (_) => hasDisallowUnsafeEval = true),
+    new OptionHandler('--hide-package-warnings', passThrough),
     new OptionHandler('-D.+=.*', addInEnvironment),
 
     // The following two options must come last.
     new OptionHandler('-.*', (String argument) {
       helpAndFail('Error: Unknown option "$argument".');
     }),
     new OptionHandler('.*', (String argument) {
       arguments.add(nativeToUriPath(argument));
     })
   ];
@@ skipping 258 matching lines @@
   --suppress-hints
     Do not display any hints.
 
   --enable-diagnostic-colors
     Add colors to diagnostic messages.
 
   --terse
     Emit diagnostics without suggestions for how to get rid of the diagnosed
     problems.
 
+  --hide-package-warnings
+    Hide warnings and hints generated from packages.
+
 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 68 matching lines @@
     }
   }
 
   try {
     return compilerMain(arguments).catchError(onError);
   } catch (exception, trace) {
     onError(exception, trace);
     return new Future.value();
   }
 }