Merge pull request swiftlang#1489 from practicalswift/swiftc-28257-swift-typechecker-resolvetypewitness

[swiftc] Add test case for crash triggered in swift::TypeChecker::resolveTypeWitness(…)

Author: gribozavr

validation-test/compiler_crashers/28257-swift-typechecker-resolvetypewitness.swift

@@ -0,0 +1,14 @@
+// RUN: not --crash %target-swift-frontend %s -parse
+
+// Distributed under the terms of the MIT license
+// Test case submitted to project by https://github.com/practicalswift (practicalswift)
+// Test case found by fuzzing
+
+protocol A{
+class A:a{
+}
+typealias e:a
+protocol a{
+typealias r
+}
+typealias e:A