Built-in apply() performance benefits from an uninitialized IC.

src/x64/builtins-x64.cc

Index: src/x64/builtins-x64.cc
diff --git a/src/x64/builtins-x64.cc b/src/x64/builtins-x64.cc
index 4fa405d55f4ec8c9bb066844448ee37d424ede9e..2d4421d7e12d811ab0730a6be325ffc671282bb8 100644
--- a/src/x64/builtins-x64.cc
+++ b/src/x64/builtins-x64.cc
@@ -1105,6 +1105,8 @@ static void Generate_PushAppliedArguments(MacroAssembler* masm,
                                           const int limitOffset) {
   Register receiver = LoadDescriptor::ReceiverRegister();
   Register key = LoadDescriptor::NameRegister();
+  Register slot = LoadDescriptor::SlotRegister();
+  Register vector = LoadWithVectorDescriptor::VectorRegister();
 
   // Copy all arguments from the array to the stack.
   Label entry, loop;
@@ -1114,7 +1116,13 @@ static void Generate_PushAppliedArguments(MacroAssembler* masm,
   __ movp(receiver, Operand(rbp, argumentsOffset));  // load arguments
 
   // Use inline caching to speed up access to arguments.
-  Handle<Code> ic = masm->isolate()->builtins()->KeyedLoadIC_Megamorphic();
+  FeedbackVectorSpec spec(0, Code::KEYED_LOAD_IC);
+  Handle<TypeFeedbackVector> feedback_vector =
+      masm->isolate()->factory()->NewTypeFeedbackVector(&spec);
+  int index = feedback_vector->GetIndex(FeedbackVectorICSlot(0));
+  __ Move(slot, Smi::FromInt(index));
+  __ Move(vector, feedback_vector);
+  Handle<Code> ic = KeyedLoadICStub(masm->isolate()).GetCode();
   __ Call(ic, RelocInfo::CODE_TARGET);
   // It is important that we do not have a test instruction after the
   // call.  A test instruction after the call is used to indicate that