swift234

Don't look into a type context to resolve types in the inheritance clause.

Instead, just check the generic parameters, then do a lookup as usual in the
enclosing context.

Fixes crash suite #58 and quite a few others (~200). This looks way more
impressive than it is; in most of these test cases it's the exact same
pattern causing the crash, and that pattern was just the last outstanding
crash trigger in a sea of garbage. (The few deleted tests were identical
to #58.)

Swift SVN r24748