Defer creating Handles for HConstants to the code generation phase.

src/hydrogen.h

Index: src/hydrogen.h
diff --git a/src/hydrogen.h b/src/hydrogen.h
index 85977c132654265721d62de343a8fc3aacd8ac24..e0c39e2a72c88fae3b78b8d3ac5c37f341454153 100644
--- a/src/hydrogen.h
+++ b/src/hydrogen.h
@@ -287,6 +287,8 @@ class HGraph: public ZoneObject {
     undefined_constant_.set(constant);
   }
   HConstant* GetConstantUndefined() const { return undefined_constant_.get(); }
+  HConstant* GetConstantInt32(SetOncePointer<HConstant>* pointer,
+                              int32_t integer_value);
   HConstant* GetConstant1();
   HConstant* GetConstantMinus1();
   HConstant* GetConstantTrue();
@@ -1195,6 +1197,9 @@ class HGraphBuilder: public AstVisitor {
 
   bool inline_bailout_;
 
+  HConstant* constant_undefined_;
+  HConstant* constant_null_;
+
   friend class FunctionState;  // Pushes and pops the state stack.
   friend class AstContext;  // Pushes and pops the AST context stack.