swift234

Sema: Base lvalue-ness of storage access on whether setter is mutating, not on kind of type.

More progress on rdar://problem/21578832. A property access off of a reference type may still require an lvalue base if it's a protocol extension implementation with a mutating setter. This gets us another step toward correct type-checking behavior, but the resulting AST still improperly loads the base reference, which leads to SILGen breakage.

Swift SVN r30837