New hydrogen instruction to reduce cost of growing an array on keyed stores.

src/arm/lithium-codegen-arm.h

Index: src/arm/lithium-codegen-arm.h
diff --git a/src/arm/lithium-codegen-arm.h b/src/arm/lithium-codegen-arm.h
index 40ab3e83e8986616dafb4726e12e1c36adef1a03..add08a1b498292a896d70c8cccfe66b749f27fb8 100644
--- a/src/arm/lithium-codegen-arm.h
+++ b/src/arm/lithium-codegen-arm.h
@@ -112,6 +112,7 @@ class LCodeGen: public LCodeGenBase {
   void DoDeferredTaggedToI(LTaggedToI* instr);
   void DoDeferredMathAbsTaggedHeapNumber(LMathAbs* instr);
   void DoDeferredStackCheck(LStackCheck* instr);
+  void DoDeferredMaybeGrowElements(LMaybeGrowElements* instr);
   void DoDeferredStringCharCodeAt(LStringCharCodeAt* instr);
   void DoDeferredStringCharFromCode(LStringCharFromCode* instr);
   void DoDeferredAllocate(LAllocate* instr);