Remove the unused, inaptly-named, and incorrect RequiresMergeCode.

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 188 matching lines @@
   void SpillAll();
 
   // Spill all occurrences of a specific register from the frame.
   void Spill(Register reg);
 
   // Spill all occurrences of an arbitrary register if possible.  Return the
   // register spilled or no_reg if it was not possible to free any register
   // (ie, they all have frame-external references).
   Register SpillAnyRegister();
 
-  // True if making the frame mergable via MakeMergable will generate code.
-  bool RequiresMergeCode();
-
   // Ensure that this frame is in a state where an arbitrary frame of the
   // right size could be merged to it.  May emit code.
   void MakeMergable();
 
   // Make this virtual frame have a state identical to an expected virtual
   // frame.  As a side effect, code may be emitted to make this frame match
   // the expected one.
   void MergeTo(VirtualFrame* expected);
 
   // Detach a frame from its code generator, perhaps temporarily.  This
@@ skipping 313 matching lines @@
   // 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);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_VIRTUAL_FRAME_IA32_H_