Eo: Fix efl_isa() sometimes returning wrong results with extensions
This fixes an issue where efl_isa() wouldn't work for extensions or
ancestors of extensions of a class.
Before this patch efl_isa(obj, F1) would return false, now it returns
true as expected.
This is just one example, there is a whole array of variations to this
issue that are now fixed.
Thanks to Gustavo for reminding me of this.