Turn the NumberToStringStub into a hydrogen stub.

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 8f27374af5f156b9c6e85ef2f6622f4fd0821ec2..1896c00f92a4eefd29202473204f5ca86ca5ec4a 100644
--- a/src/x64/code-stubs-x64.cc
+++ b/src/x64/code-stubs-x64.cc
@@ -60,6 +60,16 @@ void ToNumberStub::InitializeInterfaceDescriptor(
 }
 
 
+void NumberToStringStub::InitializeInterfaceDescriptor(
+    Isolate* isolate,
+    CodeStubInterfaceDescriptor* descriptor) {
+  static Register registers[] = { rax };
+  descriptor->register_param_count_ = 1;
+  descriptor->register_params_ = registers;
+  descriptor->deoptimization_handler_ = NULL;
+}
+
+
 void FastCloneShallowArrayStub::InitializeInterfaceDescriptor(
     Isolate* isolate,
     CodeStubInterfaceDescriptor* descriptor) {
@@ -2909,22 +2919,6 @@ void RegExpConstructResultStub::Generate(MacroAssembler* masm) {
 }
 
 
-void NumberToStringStub::Generate(MacroAssembler* masm) {
-  Label runtime;
-
-  StackArgumentsAccessor args(rsp, 1, ARGUMENTS_DONT_CONTAIN_RECEIVER);
-  __ movq(rbx, args.GetArgumentOperand(0));
-
-  // Generate code to lookup number in the number string cache.
-  __ LookupNumberStringCache(rbx, rax, r8, r9, &runtime);
-  __ ret(1 * kPointerSize);
-
-  __ bind(&runtime);
-  // Handle number to string in the runtime system if not found in the cache.
-  __ TailCallRuntime(Runtime::kNumberToStringSkipCache, 1, 1);
-}
-
-
 static int NegativeComparisonResult(Condition cc) {
   ASSERT(cc != equal);
   ASSERT((cc == less) || (cc == less_equal)