Move backend specific files to separate directories.

src/virtual-frame.h

 // Copyright 2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 180 matching lines @@
     data_.index_ = new_index;
   }
 
   friend class VirtualFrame;
 };
 
 
 } }  // namespace v8::internal
 
 #ifdef ARM
-#include "virtual-frame-arm.h"
+#include "arm/virtual-frame-arm.h"
 #else  // ia32
-#include "virtual-frame-ia32.h"
+#include "ia32/virtual-frame-ia32.h"
 #endif
 
 #endif  // V8_VIRTUAL_FRAME_H_