By adding a py__class__ method to CompiledObject and Class, we Jedi is able to understand isinstance checks, now.

This also includes a CheckAttribute class in evaluatue.compiled, because it's way easier to generalize the AttributeErrors there.

jedi/evaluate/stdlib.py

@@ -140,7 +140,7 @@ def builtins_isinstance(evaluator, obj, params):
     for o in obj:
         for cls in classes:
             try:
-                mro_func = o.base.py__mro__
+                mro_func = o.py__class__(evaluator).py__mro__
             except AttributeError:
                 return any_bool
             else: