Merge pull request #1750 from practicalswift/swiftc-28279-swift-archetypebuilder-potentialarchetype-getnestedtype

[swiftc] Add test case for crash triggered in swift::ArchetypeBuilder::PotentialArchetype::getNestedType(…)

Author: tkremenek

validation-test/compiler_crashers/28279-swift-archetypebuilder-potentialarchetype-getnestedtype.swift

@@ -0,0 +1,15 @@
+// This source file is part of the Swift.org open source project
+// Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See http://swift.org/LICENSE.txt for license information
+// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+
+// RUN: not --crash %target-swift-frontend %s -parse
+{
+protocol A{
+typealias e
+let f
+typealias e
+typealias e=b
+typealias b