Fix parsing of factory calls (issue 500).

tests/language/src/SavannahTest.dart

 // Copyright (c) 2011, 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.
 // Dart test using an identity hash.
 
-interface BigGame {
+interface BigGame extends Hashable {
   final String name;
 }
 
 class Giraffe implements BigGame {
   final String name;
   final int identityHash_;
 
   Giraffe(this.name) : identityHash_ = nextId() {}
 
   int hashCode() {
@@ skipping 58 matching lines @@
       caught = true;
     }
     Expect.equals(true, caught);
   }
 
 }
 
 main() {
   SavannahTest.testMain();
 }