[stubs] replaced ToString MacroAssembler Stub with CodeStubAssembler builtin

src/x64/code-stubs-x64.cc

Index: src/x64/code-stubs-x64.cc
diff --git a/src/x64/code-stubs-x64.cc b/src/x64/code-stubs-x64.cc
index 102265149555ae7ce245725c8cbf5a58e2f4defa..6aabf3b7ff210079bf9b306209f168aa4f9102ab 100644
--- a/src/x64/code-stubs-x64.cc
+++ b/src/x64/code-stubs-x64.cc
@@ -2232,40 +2232,6 @@ void SubStringStub::Generate(MacroAssembler* masm) {
   generator.SkipSlow(masm, &runtime);
 }
 
-void ToStringStub::Generate(MacroAssembler* masm) {
-  // The ToString stub takes one argument in rax.
-  Label is_number;
-  __ JumpIfSmi(rax, &is_number, Label::kNear);
-
-  Label not_string;
-  __ CmpObjectType(rax, FIRST_NONSTRING_TYPE, rdi);
-  // rax: receiver
-  // rdi: receiver map
-  __ j(above_equal, &not_string, Label::kNear);
-  __ Ret();
-  __ bind(&not_string);
-
-  Label not_heap_number;
-  __ CompareRoot(rdi, Heap::kHeapNumberMapRootIndex);
-  __ j(not_equal, &not_heap_number, Label::kNear);
-  __ bind(&is_number);
-  NumberToStringStub stub(isolate());
-  __ TailCallStub(&stub);
-  __ bind(&not_heap_number);
-
-  Label not_oddball;
-  __ CmpInstanceType(rdi, ODDBALL_TYPE);
-  __ j(not_equal, &not_oddball, Label::kNear);
-  __ movp(rax, FieldOperand(rax, Oddball::kToStringOffset));
-  __ Ret();
-  __ bind(&not_oddball);
-
-  __ PopReturnAddressTo(rcx);     // Pop return address.
-  __ Push(rax);                   // Push argument.
-  __ PushReturnAddressFrom(rcx);  // Push return address.
-  __ TailCallRuntime(Runtime::kToString);
-}
-
 
 void StringHelper::GenerateFlatOneByteStringEquals(MacroAssembler* masm,
                                                    Register left,