edje: optimize color_class_recursive_find_helper() function
If the color_class is not overridden by the object level the
hash will be empty but still we do the expensive call to _edje_hash_find_helper()
find the color_class in an empty hash. by checking if the hash is empty
and returning early we save lot of unnecessary hash computaion and lookup.
Reviewed By: Hermet
Differential Revision: https://phab.enlightenment.org/D9532