Add --hide-package-warnings option.

tests/compiler/dart2js/memory_compiler.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.test.memory_compiler;
 
 import 'memory_source_file_helper.dart';
 
 import '../../../sdk/lib/_internal/compiler/implementation/dart2jslib.dart'
        show NullSink;
-import '../../../sdk/lib/_internal/compiler/implementation/filenames.dart';
 
 import '../../../sdk/lib/_internal/compiler/compiler.dart'
        show Diagnostic, DiagnosticHandler;
 
 import 'dart:async';
 
 import '../../../sdk/lib/_internal/compiler/implementation/mirrors/source_mirrors.dart';
 import '../../../sdk/lib/_internal/compiler/implementation/mirrors/analyze.dart';
 
 class DiagnosticMessage {
   final Uri uri;
   final int begin;
   final int end;
   final String message;
   final Diagnostic kind;
 
   DiagnosticMessage(this.uri, this.begin, this.end, this.message, this.kind);
+
+  String toString() => '$uri:$begin:$end:$message:$kind';
 }
 
 class DiagnosticCollector {
   List<DiagnosticMessage> messages = <DiagnosticMessage>[];
 
   void call(Uri uri, int begin, int end, String message,
                          Diagnostic kind) {
     messages.add(new DiagnosticMessage(uri, begin, end, message, kind));
   }
 
   Iterable<DiagnosticMessage> filterMessagesByKind(Diagnostic kind) {
     return messages.where(
       (DiagnosticMessage message) => message.kind == kind);
   }
 
   Iterable<DiagnosticMessage> get errors {
     return filterMessagesByKind(Diagnostic.ERROR);
   }
 
   Iterable<DiagnosticMessage> get warnings {
     return filterMessagesByKind(Diagnostic.WARNING);
   }
 
   Iterable<DiagnosticMessage> get hints {
     return filterMessagesByKind(Diagnostic.HINT);
   }
+
+  Iterable<DiagnosticMessage> get infos {
+    return filterMessagesByKind(Diagnostic.INFO);
+  }
 }
 
 DiagnosticHandler createDiagnosticHandler(DiagnosticHandler diagnosticHandler,
                                           SourceFileProvider provider,
                                           bool showDiagnostics) {
   var handler = diagnosticHandler;
   if (showDiagnostics) {
     if (diagnosticHandler == null) {
       handler = new FormattingDiagnosticHandler(provider);
     } else {
@@ skipping 101 matching lines @@
       createDiagnosticHandler(diagnosticHandler, provider, showDiagnostics);
 
   List<Uri> libraries = <Uri>[];
   memorySourceFiles.forEach((String path, _) {
     libraries.add(new Uri(scheme: 'memory', path: path));
   });
 
   return analyze(libraries, libraryRoot, packageRoot,
                  provider, handler, options);
 }