Merge pull request #7895 from DougGregor/rdar30702721

Author: swift-ci

validation-test/compiler_crashers_2_fixed/0079-rdar30702721.swift

@@ -0,0 +1,9 @@
+// RUN: %target-swift-frontend %s -emit-ir
+
+extension Sequence {
+	typealias Element = Iterator.Element
+}
+
+func f<C: Sequence>(c: C) where C.Iterator == C {
+  c.makeIterator()
+}