swift234

Fix an arbitrary restriction where we would not propagate the result type of
call expression onto a callee when it was a binary expression.  Doing this
requires improving the diagnostics for when the contextual result type is
incompatible with all candidates, but that is general goodness all around.

This fixes:
<rdar://problem/22333090> QoI: Propagate contextual information in a call to operands

and improves a number of diagnostics where the problem is that an operator
is used in a context that expects a type that it cannot produce.



Swift SVN r31891