replace object types with interfaces when they appear as the supertype of an interface
replace object types with interfaces when they appear as the supertype of an interface

Summary: Flow is changing the behavior of object types to no longer be valid supertypes of classes. This replaces object types when they appear as supertypes of classes to be interfaces to avoid errors when this change rolls out.

Reviewed By: pieterv

Differential Revision: D27198604

fbshipit-source-id: 4a384baac1699ace1941930d1a41463ce05cfce8

facebook/draft-js