Always require $this on instance methods
Summary:
We removed support for calling instance methods statically already so mark them as needing a `$this`. Follow up diffs to remove the attribute entirely.
It looks like we were still allowing calling instance methods statically in two places. (1) raw `invokeFunc` from the runtime, most notably for the `86*init` functions (added a verifier pass to stop this from happening and fix some tests), and (2) `call_user_func`.
Reviewed By: ottoni, jano, alexeyt
Differential Revision:
D16060802
fbshipit-source-id:
f8c2971908d8d92fbbf08ce8706e9f7614de5c6a