Add support for metadata annotation syntax (issue 4056)

compiler/java/com/google/dart/compiler/resolver/ClassElementImplementation.java

 // 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.
 
 package com.google.dart.compiler.resolver;
 
 import com.google.common.collect.Lists;
 import com.google.dart.compiler.ast.DartClass;
 import com.google.dart.compiler.ast.DartDeclaration;
 import com.google.dart.compiler.ast.DartObsoleteMetadata;
@@ skipping 44 matching lines @@
     }
   };
 
   ClassElementImplementation(DartClass node, String name, String nativeName,
                              LibraryElement library) {
     super(node, name);
     this.nativeName = nativeName;
     this.library = library;
     if (node != null) {
       isInterface = node.isInterface();
-      metadata = node.getMetadata();
+      metadata = node.getObsoleteMetadata();
       modifiers = node.getModifiers();
       nameLocation = node.getName().getSourceInfo();
       declarationNameWithTypeParameter = new DartParameterizedTypeNode(node.getName(), node.getTypeParameters()).toSource();
     } else {
       isInterface = false;
       metadata = DartObsoleteMetadata.EMPTY;
       modifiers = Modifiers.NONE;
       nameLocation = SourceInfo.UNKNOWN;
       declarationNameWithTypeParameter = "";
     }
@@ skipping 291 matching lines @@
   @Override
   public List<Element> getUnimplementedMembers() {
     return unimplementedMembers;
   }
 
   @Override
   public void setUnimplementedMembers(List<Element> members) {
     this.unimplementedMembers = members;
   }
 }