cleans up sdk patching so we no longer have unresolved names

test/generated_sdk/lib/_internal/compiler/js_lib/interceptors.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.
 
 library _interceptors;
 
 import 'dart:_js_embedded_names' show
     DISPATCH_PROPERTY_NAME,
     MAP_TYPE_TO_INTERCEPTOR;
 
@@ skipping 386 matching lines @@
  * Interceptor for unclassified JavaScript objects, typically objects with a
  * non-trivial prototype chain.
  *
  * This class also serves as a fallback for unknown JavaScript exceptions.
  */
 class UnknownJavaScriptObject extends JavaScriptObject {
   const UnknownJavaScriptObject();
 
   String toString() => JS('String', 'String(#)', this);
 }