swift234

stdlib/Dictionary: when bridging Dictionary of non-verbatim-bridged
types to NSDictionary, perform bridging operation in O(1), and defer
bridging of the contents until the NSDictionary is accessed

There is no cache for bridged keys and values; the Swift NSDictionary
will return values with different pointer values when a given key is
repeatedly accessed.

Part of rdar://17556319

Does not fix the O(N) performance of objc thunks, because Dictionary is
not recognizing its own native storage when bridging from Objective-C.
This tracked by rdar://17010353

Swift SVN r19853