Split dart:builtin into dart:builtin and dart:io.

runtime/bin/dartutils.h

 // 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.
 
 #ifndef BIN_DARTUTILS_H_
 #define BIN_DARTUTILS_H_
 
 #include "bin/builtin.h"
 #include "include/dart_api.h"
 #include "platform/globals.h"
@@ skipping 64 matching lines @@
   static Dart_Handle LoadSource(CommandLineOptions* url_mapping,
                                 Dart_Handle library,
                                 Dart_Handle url,
                                 Dart_LibraryTag tag,
                                 const char* filename);
 
   static const char* kDartScheme;
   static const char* kBuiltinLibURL;
   static const char* kCoreLibURL;
   static const char* kCoreImplLibURL;
-  static const char* kCoreNativeWrappersLibURL;
+  static const char* kIOLibURL;
+  static const char* kNativeWrappersLibURL;
 
   static const char* kIdFieldName;
 
  private:
   static const char* GetCanonicalPath(const char* reference_dir,
                                       const char* filename);
 
   DISALLOW_ALLOCATION();
   DISALLOW_IMPLICIT_CONSTRUCTORS(DartUtils);
 };
 
 #endif  // BIN_DARTUTILS_H_