Use target-specific word instead of runtime word.

Change-Id: Ia11dc3cc520a1a5c7bd017013e5699af9570ce91
diff --git a/compiler/optimizing/code_generator_x86.h b/compiler/optimizing/code_generator_x86.h
index dd5044f..bba81c0 100644
--- a/compiler/optimizing/code_generator_x86.h
+++ b/compiler/optimizing/code_generator_x86.h
@@ -22,9 +22,10 @@
 #include "utils/x86/assembler_x86.h"
 
 namespace art {
-
 namespace x86 {
 
+static constexpr size_t kX86WordSize = 4;
+
 class LocationsBuilderX86 : public HGraphVisitor {
  public:
   explicit LocationsBuilderX86(HGraph* graph) : HGraphVisitor(graph) { }
@@ -77,6 +78,10 @@
   virtual void Bind(Label* label) OVERRIDE;
   virtual void Move(HInstruction* instruction, Location location, HInstruction* move_for) OVERRIDE;
 
+  virtual size_t GetWordSize() const OVERRIDE {
+    return kX86WordSize;
+  }
+
   virtual HGraphVisitor* GetLocationBuilder() OVERRIDE {
     return &location_builder_;
   }