Make .enclosingClass always return the declaration

pkg/compiler/lib/src/js_backend/backend.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.
 
 library js_backend.backend;
 
 import 'dart:async' show Future;
 
 import 'package:js_runtime/shared/embedded_names.dart' as embeddedNames;
 
@@ skipping 2291 matching lines @@
 
     if (mustPreserveNames) reporter.log('Preserving names.');
 
     if (mustRetainMetadata) {
       reporter.log('Retaining metadata.');
 
       compiler.libraryLoader.libraries.forEach(retainMetadataOf);
 
       StagedWorldImpactBuilder impactBuilder = enqueuer.isResolutionQueue
           ? constantImpactsForResolution
-          : constantImpactsForResolution;
+          : constantImpactsForCodegen;

[Johnni Winther, 2017/01/09 12:58:03]

Latent error found while debugging the problem in processElementMetadata.

[Siggi Cherem (dart-lang), 2017/01/11 19:24:01]

ouch

       if (enqueuer.isResolutionQueue && !enqueuer.queueIsClosed) {
         /// Register the constant value of [metadata] as live in resolution.
         void registerMetadataConstant(MetadataAnnotation metadata) {
           ConstantValue constant =
               constants.getConstantValueForMetadata(metadata);
           Dependency dependency =
               new Dependency(constant, metadata.annotatedElement);
           metadataConstants.add(dependency);
           computeImpactForCompileTimeConstant(
               dependency.constant, impactBuilder, enqueuer.isResolutionQueue);
@@ skipping 30 matching lines @@
 
     void processElementMetadata(Element element) {
       if (_registeredMetadata.add(element)) {
         element.metadata.forEach(onMetadata);
         if (element.isFunction) {
           FunctionElement function = element;
           for (ParameterElement parameter in function.parameters) {
             parameter.metadata.forEach(onMetadata);
           }
         }
-        if (element.enclosingClass != null) {
-          processElementMetadata(element.enclosingClass);
+        if (element.enclosingElement is ClassElement) {
+          // Use [enclosingElement] to process patch class metadata for patch

[Siggi Cherem (dart-lang), 2017/01/11 19:24:02]

nit: maybe highlight also that you are not using enclosingClass for that reason?

[Johnni Winther, 2017/01/12 09:56:56]

Done.

+          // and injected members.
+          processElementMetadata(element.enclosingElement);
         } else {
           processLibraryMetadata(element.library);
         }
       }
     }
 
     entities.forEach(processElementMetadata);
   }
 
   void onQueueClosed() {
@@ skipping 899 matching lines @@
   @override
   bool isNativeClass(ClassElement element) {
     return helpers.backend.isNative(element);
   }
 
   @override
   bool isNativeMember(MemberElement element) {
     return helpers.backend.isNative(element);
   }
 }