Add support for metadata annotation syntax (issue 4056)

compiler/java/com/google/dart/compiler/resolver/TopLevelElementBuilder.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.annotations.VisibleForTesting;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
 import com.google.common.collect.Sets;
@@ skipping 226 matching lines @@
       return null;
     }
 
     @Override
     public Void visitField(DartField node) {
       Modifiers modifiers = node.getModifiers();
       if (modifiers.isFinal()) {
         // final top-level fields are implicitly compile-time constants.
         modifiers = modifiers.makeConstant();
       }
-      node.setElement(Elements.fieldFromNode(node, library, node.getMetadata(), modifiers));
+      node.setElement(Elements.fieldFromNode(node, library, node.getObsoleteMetadata(), modifiers));
       return null;
     }
   }
 }