swift234

[Parse] Treat ! as a postfix operator when both left- and right-bound.

For most operators, an expression like "a@b" is lexed with '@' as a binary
operation on 'a' and 'b'. However, we want to make sure we can support
calling optional functions using the syntax "a!()". Consequently, if there
are no spaces around a single '!' token, it is treated as a postfix operator
instead of an infix operator. The infix interpretation can still be requested
by using spaces on both sides of the operator.

Swift SVN r7651