Inline Array.shift() fast path instead of using a code stub.

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index 2cfda626613b41c248dad99fb945c5f1a91eedb2..3033c46d99b69ffc605f61c58ca75c9ffbb445b2 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -4377,15 +4377,6 @@ void LCodeGen::DoTransitionElementsKind(LTransitionElementsKind* instr) {
 }
 
 
-void LCodeGen::DoArrayShift(LArrayShift* instr) {
-  ASSERT(ToRegister(instr->context()).is(rsi));
-  ASSERT(ToRegister(instr->object()).is(rax));
-  ASSERT(ToRegister(instr->result()).is(rax));
-  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());