[lworld] Javac should switch to reference projection before walking type hierarchy.

The following is documented in https://github.com/openjdk/valhalla/pull/32 as a known issue that has been deliberately deferred to a later iteration:

Class hierarchy walking in a world where inline types are islands calls for a type switch. I have done this only in places uncovered by existing tests. We need to go through various utility methods (similar to what is done in Symbol.java and Resolve.java) to make sure these changes are consistently applied.

This ticket is to follow up on this. JDK-8244711 covers this for interface implementation checks.