[Omit needless words] Treat "Mask" as a skippable type suffix.
[Omit needless words] Treat "Mask" as a skippable type suffix.

Fixes rdar://problem/23751733.

khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift