Make .enclosingClass always return the declaration

pkg/compiler/lib/src/js_backend/backend.dart

Index: pkg/compiler/lib/src/js_backend/backend.dart
diff --git a/pkg/compiler/lib/src/js_backend/backend.dart b/pkg/compiler/lib/src/js_backend/backend.dart
index 95cd78e7fb3f04afeb61c3516fa74729956eb252..2485a07319781491eefde4999e45fa5241788466 100644
--- a/pkg/compiler/lib/src/js_backend/backend.dart
+++ b/pkg/compiler/lib/src/js_backend/backend.dart
@@ -2309,7 +2309,7 @@ class JavaScriptBackend extends Backend {
 
       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) {
@@ -2360,8 +2360,10 @@ class JavaScriptBackend extends Backend {
             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);
         }