swift234

Use full DeclNames for dynamic lookup of calls.

Previously, we were just using the base name, which resulted in massive
inefficiency when dealing with Clang (we basically had to check every
selector in the system to see if it had the same first selector piece).
I've hacked ConstraintSystem a bit to carry a map from UnresolvedDotExpr
to the ApplyExpr that consumes it, so that we can use the full DeclName
and look up methods by full selector.

Now that dynamic lookup is fast, re-enable it for the
Foundation_bridge.swift test. (r17520 actually provided most of the benefit.)

This does break selector lookup on AnyObject when doing selector splitting,
and slightly regresses diagnostics when you try to call a method on AnyObject
and forget a parameter name.

<rdar://problem/16808651>. Part of the Playground performance efforts.

Swift SVN r17524