Do this by only warning on self-referential uses of a variable when there's
not another binding found in the local scope. This probably still restricts
some reasonable edge cases, but it at least allows shadowing the variable
with a local name.
<rdar://problem/17087232>
Swift SVN r18771
There's a lot more work to do here, but start to categorize tests
along the lines of what a specification might look like, with
directories (chapters) for basic concepts, declarations, expressions,
statements, etc.
Swift SVN r9958
