Speed up common ObjectProtoToString cases

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index 63832a580f6d1f6b3bab706798da78f9c72fc254..d6dfdcecc563bf02887510176fcb28f3585a5a4c 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -1587,7 +1587,6 @@ void Genesis::InitializeGlobal(Handle<JSGlobalObject> global_object,
     Handle<JSFunction> cons = factory->NewFunction(name);
     JSFunction::SetInstancePrototype(cons,
         Handle<Object>(native_context()->initial_object_prototype(), isolate));
-    cons->shared()->set_instance_class_name(*name);

[adamk, 2016/05/18 16:07:58]

This in the below are just cleanup because JSON and Math aren't constructible,
correct?

[Toon Verwaest, 2016/05/18 17:17:20]

It actually affects Object.prototype.toString.call(JSON) after deleting
toStringTag. I can either add a test and update the description, or move it out
of the CL...

[adamk, 2016/05/18 17:46:05]

Let's move it out of this CL, leaving it as a pure perf win, and do it in a
followup along with a test case.

     Handle<JSObject> json_object = factory->NewJSObject(cons, TENURED);
     DCHECK(json_object->IsJSObject());
     JSObject::AddProperty(global, name, json_object, DONT_ENUM);
@@ -1599,7 +1598,6 @@ void Genesis::InitializeGlobal(Handle<JSGlobalObject> global_object,
     JSFunction::SetInstancePrototype(
         cons,
         Handle<Object>(native_context()->initial_object_prototype(), isolate));
-    cons->shared()->set_instance_class_name(*name);
     Handle<JSObject> math = factory->NewJSObject(cons, TENURED);
     DCHECK(math->IsJSObject());
     JSObject::AddProperty(global, name, math, DONT_ENUM);