Frame layout change

This CL slightly changes the frame layout to remove an old unnecessary
slot, allow for the inclusion of compiler-generated temps and
unifies all variable offset calculation into a single function shared
by the compilers and the runtime system.

   o Update the GetVRegOffset function in stack.cc to understand the
     new layout.

   o Remove compiler-private offset calculation code and route
     everything through the shared GetVRegOffset in thread.cc.

   o Remove "filler word" that existed immediately after the last
     Dalvik local.  This was there to address an initial concern that
     I had about a single argument register being reused later as a
     long.  Now convinced that it won't happen.

   o Extend the old "padding" region to include compiler-created temps
     that can appear to the rest of the rest of the system as
     Dalvik registers.  The new temps will have Dalvik register numbers
     of -2 and lower.

   o Treat Method* for the current method as a special Dalvik register
     denoted by reg number -1.

Change-Id: I5b5f3aef9c6a01d3a647ced6ec06981ed228c785
diff --git a/src/stack.h b/src/stack.h
index 382ad24..9093cb1 100644
--- a/src/stack.h
+++ b/src/stack.h
@@ -59,6 +59,8 @@
 
   uintptr_t LoadCalleeSave(int num) const;
 
+  static int GetVRegOffset(const DexFile::CodeItem* code_item, uint32_t core_spills,
+                           uint32_t fp_spills, size_t frame_size, int reg);
 
   uint32_t GetVReg(const DexFile::CodeItem* code_item, uint32_t core_spills, uint32_t fp_spills,
                     size_t frame_size, int vreg) const;