Fix various nits in VM patch files.

runtime/bin/builtin.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 builtin;
 // NOTE: Do not import 'dart:io' in builtin.
 import 'dart:async';
 import 'dart:collection';
-import 'dart:_internal';
+import 'dart:_internal' hide Symbol;
 import 'dart:isolate';
 import 'dart:typed_data';
 
 // Embedder sets this to true if the --trace-loading flag was passed on the
 // command line.
 bool _traceLoading = false;
 
 
 // Before handling an embedder entrypoint we finalize the setup of the
 // dart:_builtin library.
@@ skipping 366 matching lines @@
     if (_traceLoading) {
       _log("Exception when resolving package URI: $packageUri");
     }
     result = null;
   }
   if (_traceLoading) {
     _log("Resolved '$packageUri' to '$result'");
   }
   return result;
 }