Inline caches: be more robust in the presence of framework change.

What used to be a class could be changed into an interface. Test for
that case as well.

Test: test.py
Bug: 194817322
(cherry picked from commit 4fba66c84245be79b1b32cbfa1584cfc5a87f053)

Merged-In: I4c225640b45c529d440faa701ed29f978b7cbd28
Change-Id: I7b133aa60bfe0c35cb3704a62b88de53d3109d93