Update dart2js diagnostics to prepare for filtering.

tests/compiler/dart2js/compiler_test.dart

 // Copyright (c) 2012, 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.
 
 import "package:expect/expect.dart";
 import "../../../sdk/lib/_internal/compiler/implementation/dart2jslib.dart";
 import "../../../sdk/lib/_internal/compiler/implementation/elements/elements.dart";
 import "../../../sdk/lib/_internal/compiler/implementation/resolution/resolution.dart";
 import "../../../sdk/lib/_internal/compiler/implementation/tree/tree.dart";
 import "../../../sdk/lib/_internal/compiler/implementation/util/util.dart";
 import "mock_compiler.dart";
 import "parser_helper.dart";
 
 class CallbackMockCompiler extends MockCompiler {
   CallbackMockCompiler();
 
   var onError;
   var onWarning;
 
   setOnError(var f) => onError = f;
   setOnWarning(var f) => onWarning = f;
 
-  void reportWarning(Node node, var message) {
-    if (onWarning != null) onWarning(this, node, message);
-    super.reportWarning(node, message);
+  void reportWarning(Spannable node,
+                     MessageKind errorCode,
+                     [Map arguments = const {}]) {
+    if (onWarning != null) onWarning(this, node, errorCode.error(arguments));
+    super.reportWarning(node, errorCode, arguments);
   }
 
   void reportError(Spannable node,
                    MessageKind errorCode,
                    [Map arguments = const {}]) {
     if (onError != null) onError(this, node, errorCode.error(arguments));
     super.reportError(node, errorCode, arguments);
   }
 }
 
 testErrorHandling() {
   // Test that compiler.currentElement is set correctly when
   // reporting errors/warnings.
   CallbackMockCompiler compiler = new CallbackMockCompiler();
   ResolverVisitor visitor = compiler.resolverVisitor();
   compiler.parseScript('NoSuchPrefix.NoSuchType foo() {}');
   FunctionElement foo = compiler.mainApp.find('foo');
   compiler.setOnWarning(
       (c, n, m) => Expect.equals(foo, compiler.currentElement));
   foo.computeType(compiler);
   Expect.equals(1, compiler.warnings.length);
 }
 
 main() {
   testErrorHandling();
 }