Support metadata on patches.

pkg/compiler/lib/src/js_emitter/metadata_collector.dart

 // Copyright (c) 2013, 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.
 
 part of dart2js.js_emitter;
 
 /// Represents an entry's position in one of the global metadata arrays.
 ///
 /// [_rc] is used to count the number of references of the token in the
 /// ast for a program.
@@ skipping 143 matching lines @@
   /// The metadata function returns the metadata associated with
   /// [element] in generated code.  The metadata needs to be wrapped
   /// in a function as it refers to constants that may not have been
   /// constructed yet.  For example, a class is allowed to be
   /// annotated with itself.  The metadata function is used by
   /// mirrors_patch to implement DeclarationMirror.metadata.
   jsAst.Fun buildMetadataFunction(Element element) {
     if (!_mustEmitMetadataFor(element)) return null;
     return _compiler.withCurrentElement(element, () {
       List<jsAst.Expression> metadata = <jsAst.Expression>[];
-      Link link = element.metadata;
-      // TODO(ahe): Why is metadata sometimes null?
-      if (link != null) {
-        for (; !link.isEmpty; link = link.tail) {
-          MetadataAnnotation annotation = link.head;
-          ConstantValue constant =
-              _backend.constants.getConstantValueForMetadata(annotation);
-          if (constant == null) {
-            _compiler.internalError(annotation, 'Annotation value is null.');
-          } else {
-            metadata.add(_emitter.constantReference(constant));
-          }
+      for (MetadataAnnotation annotation in element.metadata) {
+        ConstantValue constant =
+            _backend.constants.getConstantValueForMetadata(annotation);
+        if (constant == null) {
+          _compiler.internalError(annotation, 'Annotation value is null.');
+        } else {
+          metadata.add(_emitter.constantReference(constant));
         }
       }
       if (metadata.isEmpty) return null;
       return js('function() { return # }',
           new jsAst.ArrayInitializer(metadata));
     });
   }
 
   List<jsAst.DeferredNumber> reifyDefaultArguments(FunctionElement function) {
     FunctionSignature signature = function.functionSignature;
@@ skipping 96 matching lines @@
         result.finalize(_globalTypesCounter++);
       }
       return result;
     });
   }
 
   List<jsAst.DeferredNumber> computeMetadata(FunctionElement element) {
     return _compiler.withCurrentElement(element, () {
       if (!_mustEmitMetadataFor(element)) return const <jsAst.DeferredNumber>[];
       List<jsAst.DeferredNumber> metadata = <jsAst.DeferredNumber>[];
-      Link link = element.metadata;
-      // TODO(ahe): Why is metadata sometimes null?
-      if (link != null) {
-        for (; !link.isEmpty; link = link.tail) {
-          metadata.add(reifyMetadata(link.head));
-        }
+      for (MetadataAnnotation annotation in element.metadata) {
+        metadata.add(reifyMetadata(annotation));
       }
       return metadata;
     });
   }
 
   @override
   void finalizeTokens() {
     bool checkTokensInTypes(OutputUnit outputUnit, entries) {
       UnBoundDebugger debugger = new UnBoundDebugger(outputUnit);
       for (_BoundMetadataEntry entry in entries) {
@@ skipping 60 matching lines @@
     if (token is _ForwardingMetadataEntry && !token.isBound) {
       _foundUnboundToken = true;
     }
   }
 
   bool findUnboundPlaceholders(jsAst.Node node) {
     node.accept(this);
     return _foundUnboundToken;
   }
 }