Refactor the use of Method by the oat compiler.

Change-Id: Ib0ee18ed06846f82567f746edc7a5049dc6215df
diff --git a/src/compiler/codegen/arm/ArmRallocUtil.cc b/src/compiler/codegen/arm/ArmRallocUtil.cc
index 81c721d..5d2c4e6 100644
--- a/src/compiler/codegen/arm/ArmRallocUtil.cc
+++ b/src/compiler/codegen/arm/ArmRallocUtil.cc
@@ -111,7 +111,7 @@
  */
 extern void oatDoPromotion(CompilationUnit* cUnit)
 {
-    int numRegs = cUnit->method->NumRegisters();
+    int numRegs = cUnit->numDalvikRegisters;
 
     /*
      * TUNING: is leaf?  Can't just use "hasInvoke" to determine as some