swift234

Parse trailing closure productions as expr-postfix.

This is more naturally where they belong in the grammar, allows for nice chained transformation calls like 'x.map { ... }.filter { ... }', and lets us remove a bunch of kludgy fixits to try to handle the 'wanted to parse postfix but didn't' case. Fixes <rdar://problem/14098078>. Also fix the special-case handling of "builder pattern" style method chains to parse 'x\n.method{' as a chained method call, like it does 'x\n.method(' or 'x\n.property['. (There's got to be a better way...)

Swift SVN r8828