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

src/x64/lithium-x64.cc

Index: src/x64/lithium-x64.cc
diff --git a/src/x64/lithium-x64.cc b/src/x64/lithium-x64.cc
index 3989db2580ede5ab19f3fd9496ad022439c337a1..01aeedc419f01fd9ec8eafb2a056c6113d8250c0 100644
--- a/src/x64/lithium-x64.cc
+++ b/src/x64/lithium-x64.cc
@@ -2263,14 +2263,6 @@ LInstruction* LChunkBuilder::DoTransitionElementsKind(
 }
 
 
-LInstruction* LChunkBuilder::DoArrayShift(HArrayShift* instr) {
-  LOperand* object = UseFixed(instr->object(), rax);
-  LOperand* context = UseFixed(instr->context(), rsi);
-  LArrayShift* result = new(zone()) LArrayShift(context, object);
-  return MarkAsCall(DefineFixed(result, rax), instr, CANNOT_DEOPTIMIZE_EAGERLY);
-}
-
-
 LInstruction* LChunkBuilder::DoTrapAllocationMemento(
     HTrapAllocationMemento* instr) {
   LOperand* object = UseRegister(instr->object());