swift234

"Properly" compute the depth of Self in ill-formed protocol declarations.

Rather than always using depth 0 for the Self generic type parameter
of a protocol, which is the correct value in well-formed code,
actually compute the depth based on the context. This maintains the
depth invariants of the AST in ill-formed code, resolving a large
number of crashers (169), including rdar://problem/21042357, and
regresses one crasher.

Swift SVN r28920