Improve Array.shift() performance for small arrays.

src/arm/lithium-codegen-arm.cc

Index: src/arm/lithium-codegen-arm.cc
diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index 5a01d3bc84205a4b38868f142295cb7969e99e92..929f57d990a512777ee748398b9f6e47001b13d9 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -4435,6 +4435,15 @@ void LCodeGen::DoTransitionElementsKind(LTransitionElementsKind* instr) {
 }
 
 
+void LCodeGen::DoArrayShift(LArrayShift* instr) {
+  ASSERT(ToRegister(instr->context()).is(cp));
+  ASSERT(ToRegister(instr->object()).is(r0));
+  ASSERT(ToRegister(instr->result()).is(r0));
+  ArrayShiftStub stub(isolate(), instr->hydrogen()->kind());
+  CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
+}
+
+
 void LCodeGen::DoTrapAllocationMemento(LTrapAllocationMemento* instr) {
   Register object = ToRegister(instr->object());
   Register temp = ToRegister(instr->temp());