Fixed enum binding support (issue #49)

test/com/google/gwt/inject/client/binding/Color.java

 /*
  * Copyright 2008 Google Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  * use this file except in compliance with the License. You may obtain a copy of
  * the License at
  *
  * http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  * License for the specific language governing permissions and limitations under
  * the License.
  */
 package com.google.gwt.inject.client.binding;
 
 public enum Color {
-  Red, Green, Yellow
+  Red,
+  Green,
+  Yellow() {
+    @Override public String getAlternative() {
+      return "Orange";
+    }
+  };
+
+  public String getAlternative() {
+    return this.name();
+  }
 }