Update String.fromCharCodes from sdk

tool/input_sdk/patch/internal_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:_js_primitives' show printString;
-import 'dart:_js_helper' show JS, patch;
+import 'dart:_js_helper' show patch;
 import 'dart:_interceptors' show JSArray;
 
 @patch
 class Symbol implements core.Symbol {
   @patch
   const Symbol(String name)
       : this._name = name;
 }
 
 @patch
 void printToConsole(String line) {
   printString('$line');
 }
 
 @patch
 List/*<E>*/ makeListFixedLength/*<E>*/(List/*<E>*/ growableList) {
   JSArray.markFixedList(growableList);
   return growableList;
 }
 
 @patch
 List/*<E>*/ makeFixedListUnmodifiable/*<E>*/(List/*<E>*/ list) {
   JSArray.markUnmodifiableList(list);
   return list;
 }