Turn ToNumberStub into a hydrogen code stub.

src/code-stubs-hydrogen.cc

Index: src/code-stubs-hydrogen.cc
diff --git a/src/code-stubs-hydrogen.cc b/src/code-stubs-hydrogen.cc
index 324dfa9f76a4f1965a85d7da1ea36accdb3ab474..f154bad23adb3248959846787eabaf28a29fad34 100644
--- a/src/code-stubs-hydrogen.cc
+++ b/src/code-stubs-hydrogen.cc
@@ -307,6 +307,37 @@ static Handle<Code> DoGenerateCode(Stub* stub) {
 
 
 template <>
+HValue* CodeStubGraphBuilder<ToNumberStub>::BuildCodeStub() {
+  HValue* value = GetParameter(0);
+
+  // Check if the parameter is already a SMI or heap number.
+  IfBuilder if_number(this);
+  if_number.If<HIsSmiAndBranch>(value);
+  if_number.OrIf<HCompareMap>(value, isolate()->factory()->heap_number_map());
+  if_number.Then();
+
+  // Return the number.
+  Push(value);
+
+  if_number.Else();
+
+  // Convert the parameter to number using the builtin.
+  HValue* function = AddLoadJSBuiltin(Builtins::TO_NUMBER, context());
+  Add<HPushArgument>(value);
+  Push(Add<HInvokeFunction>(context(), function, 1));
+
+  if_number.End();
+
+  return Pop();
+}
+
+
+Handle<Code> ToNumberStub::GenerateCode() {
+  return DoGenerateCode(this);
+}
+
+
+template <>
 HValue* CodeStubGraphBuilder<FastCloneShallowArrayStub>::BuildCodeStub() {
   Zone* zone = this->zone();
   Factory* factory = isolate()->factory();