template<T> is not needed for V8DOMConfiguration::configureAttribute(). We can remove the template and de-inline the method. Given that SetAccessor() does a bunch of complicated stuff, de-inlining V8DOMConfiguration::configureAttribute() would make sense.
Sorry, I was confused. Please ignore this bug. configureAttribute() can be called for both ObjectTemplate and Object, so it needs to be implemented by template<T>, where T is ObjectTemplate or Object.