Prepare for removal of source_filter.gypi:

runtime/bin/platform_win.cc

 // 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.
 
+#include "platform/globals.h"
+#if defined(TARGET_OS_WINDOWS)
+
 #include "bin/platform.h"
 #include "bin/log.h"
 #include "bin/socket.h"
 
 bool Platform::Initialize() {
   // Nothing to do on Windows.
   return true;
 }
 
 
@@ skipping 38 matching lines @@
   }
   FreeEnvironmentStringsW(strings);
   return result;
 }
 
 
 void Platform::FreeEnvironment(char** env, int count) {
   for (int i = 0; i < count; i++) free(env[i]);
   delete[] env;
 }
+
+#endif  // defined(TARGET_OS_WINDOWS)