swift234

Reclaim "in" as an identifier

In Swift the "in" keyword is really a form of punctuation, and highly
context specific punctuation at that. It never begins a statement, nor
does the grammar require it be statement keyword. The grammar also
doesn't use it outside of for-each loops, and its use within a for-each
loop is highly unambiguous.

Thanks to Chris for the performance related feedback. This improves the
performance of getter/setter parsing as well.

Swift SVN r3880