Change NotImplementedException to UnimplementedError.

lib/html/src/native_DOMImplementation.dart

 // 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.
 
 class _Utils {
   static List convertToList(List list) {
     // FIXME: [possible optimization]: do not copy the array if Dart_IsArray is fine w/ it.
     final length = list.length;
     List result = new List(length);
     result.setRange(0, length, list);
     return result;
   }
 
   static List convertMapToList(Map map) {
     List result = [];
     map.forEach((k, v) => result.addAll([k, v]));
     return result;
   }
 
   static void populateMap(Map result, List list) {
     for (int i = 0; i < list.length; i += 2) {
       result[list[i]] = list[i + 1];
     }
   }
 
   static bool isMap(obj) => obj is Map;
 
   static Map createMap() => {};
 
-  static makeNotImplementedException(String fileName, int lineNo) {
+  static makeUnimplementedError(String fileName, int lineNo) {
     return new UnsupportedError('[info: $fileName:$lineNo]');
   }
 
   static window() native "Utils_window";
   static print(String message) native "Utils_print";
   static SendPort spawnDomFunctionImpl(Function topLevelFunction) native "Utils_spawnDomFunction";
   static int _getNewIsolateId() native "Utils_getNewIsolateId";
   static bool shadowRootSupported(Document document) native "Utils_shadowRootSupported";
 }
 
@@ skipping 65 matching lines @@
   bool get isEmpty => Maps.isEmpty(this);
 }
 
 get _printClosure => (s) {
   try {
     window.console.log(s);
   } catch (_) {
     _Utils.print(s);
   }
 };