Fix various nits in VM patch files.

runtime/lib/developer.dart

 // Copyright (c) 2015, 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:isolate';
-import 'dart:_internal';
+import 'dart:_internal' hide Symbol;
 
 @patch bool debugger({bool when: true,
                      String message}) native "Developer_debugger";
 
 @patch Object inspect(Object object) native "Developer_inspect";
 
 @patch void log(String message,
                 {DateTime time,
                  int sequenceNumber,
                  int level: 0,
@@ skipping 137 matching lines @@
 
 @patch int _getServiceMinorVersion() native "Developer_getServiceMinorVersion";
 
 @patch void _getServerInfo(SendPort sendPort) native "Developer_getServerInfo";
 
 @patch void _webServerControl(SendPort sendPort, bool enable)
     native "Developer_webServerControl";
 
 @patch String _getIsolateIDFromSendPort(SendPort sendPort)
     native "Developer_getIsolateIDFromSendPort";