Extract DiagnosticReporter implementation from Compiler.

tests/compiler/dart2js/js_spec_string_test.dart

 // Copyright (c) 2014, 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.
 
 // Unit test of the [NativeBehavior.processSpecString] method.
 
 import 'package:expect/expect.dart';
 import 'package:compiler/src/native/native.dart';
 import 'package:compiler/src/diagnostics/diagnostic_listener.dart';
 import 'package:compiler/src/diagnostics/messages.dart';
 import 'package:compiler/src/universe/side_effects.dart'
     show SideEffects;
 
 const OBJECT = 'Object';
 const NULL = 'Null';
 
-class Listener extends DiagnosticListener {
+class Listener extends DiagnosticReporter {
   String errorMessage;
   internalError(spannable, message) {
     errorMessage = message;
     throw "error";
   }
   reportError(message, [infos]) {
 
     errorMessage =
         '${message.message.arguments}'; // E.g.  "{text: Duplicate tag 'new'.}"
     throw "error";
@@ skipping 256 matching lines @@
   test('gvn:false', expectedGvn: false);
   test('returns:A;gvn:true', returns: ['A'], expectedGvn: true);
   test(' gvn : true ;  returns:A;', returns: ['A'], expectedGvn: true);
   test('gvn:true;returns:A;gvn:true', expectError: true);
 
   test('gvn: true; new: true', expectError: true);
   test('gvn: true; new: false', expectedGvn: true, expectedNew: false);
   test('gvn: false; new: true', expectedGvn: false, expectedNew: true);
   test('gvn: false; new: false', expectedGvn: false, expectedNew: false);
 }