Change VirtualFrame::AdjustCopies to mark target as invalid.

src/virtual-frame-ia32.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 417 matching lines @@
   // Used in the implementation of MergeTo().
   void MergeMoveRegistersToRegisters(VirtualFrame* expected);
 
   // Make the memory-to-register and constant-to-register moves
   // needed to make this frame equal the expected frame.
   // Called after all register-to-memory and register-to-register
   // moves have been made.  After this function returns, the frames
   // should be equal.
   void MergeMoveMemoryToRegisters(VirtualFrame* expected);
 
-  // Helper function to implement the copy-on-write semantics of an
-  // element's copies just before writing to the element.  The copies
-  // are updated, but the element is not changed.  A copy of the new
-  // backing store of all the copies is returned if there were any
-  // copies and in invalid frame element is returned if there were no
-  // copies.
-  FrameElement AdjustCopies(int index);
+  // Invalidates a frame slot (puts an invalid frame element in it).
+  // Copies on the frame are correctly handled, and if this slot was
+  // the backing store of copies, the index of the new backing store
+  // is returned.  Otherwise, returns kIllegalIndex.
+  // Register counts are correctly updated.
+  int InvalidateFrameSlotAt(int index);
 
   // Call a code stub that has already been prepared for calling (via
   // PrepareForCall).
   Result RawCallStub(CodeStub* stub, int frame_arg_count);
 
   // Calls a code object which has already been prepared for calling
   // (via PrepareForCall).
   Result RawCallCodeObject(Handle<Code> code, RelocInfo::Mode rmode);
 
   bool Equals(VirtualFrame* other);
 
   friend class JumpTarget;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_VIRTUAL_FRAME_IA32_H_