Patches to support Dart VM patch files in dart2js.

pkg/compiler/lib/src/js_backend/patch_resolver.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.
 
 library dart2js.js_backend.patch_resolver;
 
 import '../common.dart';
 import '../common/resolution.dart' show Resolution;
 import '../common/tasks.dart' show CompilerTask;
 import '../compiler.dart' show Compiler;
 import '../dart_types.dart';
 import '../elements/elements.dart';
 import '../elements/modelx.dart';
 import '../tree/tree.dart';
 
 class PatchResolverTask extends CompilerTask {
   PatchResolverTask(Compiler compiler) : super(compiler);
 
   Resolution get resolution => compiler.resolution;
 
   String get name => 'JavaScript patch resolver';
 
-  FunctionElement resolveExternalFunction(FunctionElementX element) {
+  FunctionElement resolveExternalFunction(FunctionElementX element)
+      => measureElement(element, () {
     if (element.isPatched) {
       FunctionElementX patch = element.patch;
       reporter.withCurrentElement(patch, () {
         patch.computeType(resolution);
       });
       checkMatchingPatchSignatures(element, patch);
       element = patch;
     } else if (!compiler.backend.isJsInterop(element)) {
       reporter.reportErrorMessage(
           element, MessageKind.PATCH_EXTERNAL_WITHOUT_IMPLEMENTATION);
     }
     return element;
-  }
+  });
 
   void checkMatchingPatchParameters(FunctionElement origin,
       List<Element> originParameters, List<Element> patchParameters) {
     assert(originParameters.length == patchParameters.length);
     for (int index = 0; index < originParameters.length; index++) {
       ParameterElementX originParameter = originParameters[index];
       ParameterElementX patchParameter = patchParameters[index];
       // TODO(johnniwinther): Remove the conditional patching when we never
       // resolve the same method twice.
       if (!originParameter.isPatched) {
@@ skipping 105 matching lines @@
           'originParameterCount': originSignature.optionalParameterCount,
           'patchParameterCount': patchSignature.optionalParameterCount
         });
       });
     } else {
       checkMatchingPatchParameters(origin, originSignature.optionalParameters,
           patchSignature.optionalParameters);
     }
   }
 }