Add import of dart:typed_data in dart:convert.

runtime/lib/convert_patch.dart

 // Copyright (c) 2013, 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.
 
-import "dart:typed_data";
-
 // JSON conversion.
 
 patch _parseJson(String json, reviver(var key, var value)) {
   _BuildJsonListener listener;
   if (reviver == null) {
     listener = new _BuildJsonListener();
   } else {
     listener = new _ReviverJsonListener(reviver);
   }
   new _JsonParser(json, listener).parse();
@@ skipping 551 matching lines @@
   }
 
   static double _parseDouble(String source, int start, int end)
       native "Double_parse";
 
   void fail(int position, [String message]) {
     if (message == null) message = "Unexpected character";
     throw new FormatException(message, source, position);
   }
 }