* Give Sequence a top-level Element, constrain Iterator to match
* Remove many instances of Iterator.
* Fixed various hard-coded tests
* XFAIL a few tests that need further investigation
* Change assoc type for arrayLiteralConvertible
* Mop up remaining "better expressed as a where clause" warnings
* Fix UnicodeDecoders prototype test
* Fix UIntBuffer
* Fix hard-coded Element identifier in CSDiag
* Fix up more tests
* Account for flatMap changes
We must order protocol typealiases *after* other types, so that
if a protocol typealias is equal to an associated type, the
representative is chosen to be the associated type and not the
typealias.
Fixes <https://bugs.swift.org/browse/SR-3687> and
<rdar://problem/30118513>.
