Warn user if DART_SDK does not match editor SDK

editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/DartUIMessages.java

 /*
  * Copyright (c) 2012, the Dart project authors.
  * 
  * Licensed under the Eclipse Public License v1.0 (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.eclipse.org/legal/epl-v10.html
  * 
  * 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
@@ skipping 151 matching lines @@
 
   static {
     NLS.initializeMessages(BUNDLE_NAME, DartUIMessages.class);
   }
 
   public static String HistoryListAction_remove;
 
   public static String HistoryListAction_max_entries_constraint;
   public static String HistoryListAction_remove_all;
 
+  public static String DartSdkInvalid_title;
+  public static String DartSdkInvalid_doesNotExist;
+  public static String DartSdkInvalid_notEqual;
+  public static String DartSdkInvalid_dontShowAgain;
+
   private DartUIMessages() {
     // Do not instantiate
   }
 
 }