[stubs] Unify (and optimize) implementation of ToObject.

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 8e782158cc68120da5ec8195991899564a596281..c8b132105179d3ee51ea6c1f16a30e88117d38bb 100644
--- a/src/x64/builtins-x64.cc
+++ b/src/x64/builtins-x64.cc
@@ -1053,8 +1053,9 @@ void Builtins::Generate_FunctionCall(MacroAssembler* masm) {
       __ Integer32ToSmi(rax, rax);
       __ Push(rax);
 
-      __ Push(rbx);
-      __ InvokeBuiltin(Builtins::TO_OBJECT, CALL_FUNCTION);
+      __ movp(rax, rbx);
+      ToObjectStub stub(masm->isolate());
+      __ CallStub(&stub);
       __ movp(rbx, rax);
       __ Set(rdx, 0);  // indicate regular JS_FUNCTION
 
@@ -1274,8 +1275,9 @@ static void Generate_ApplyHelper(MacroAssembler* masm, bool targetIsArgument) {
 
     // Convert the receiver to an object.
     __ bind(&call_to_object);
-    __ Push(rbx);
-    __ InvokeBuiltin(Builtins::TO_OBJECT, CALL_FUNCTION);
+    __ movp(rax, rbx);
+    ToObjectStub stub(masm->isolate());
+    __ CallStub(&stub);
     __ movp(rbx, rax);
     __ jmp(&push_receiver, Label::kNear);