Fix DoubleStackSlot-to-DoubleStackSlot moves on ia32. Unify platform-independent code.

src/lithium.h

 // Copyright 2012 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 691 matching lines @@
   CompilationInfo* info_;
   HGraph* const graph_;
   BitVector* allocated_double_registers_;
   ZoneList<LInstruction*> instructions_;
   ZoneList<LPointerMap*> pointer_maps_;
   ZoneList<Handle<JSFunction> > inlined_closures_;
 };
 
 
 int ElementsKindToShiftSize(ElementsKind elements_kind);
+int StackSlotOffset(int index);
 
 enum NumberUntagDMode {
   NUMBER_CANDIDATE_IS_SMI,
   NUMBER_CANDIDATE_IS_SMI_OR_HOLE,
   NUMBER_CANDIDATE_IS_SMI_CONVERT_HOLE,
   NUMBER_CANDIDATE_IS_ANY_TAGGED
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_LITHIUM_H_