Add validation test for fixed crasher

Author: slavapestov

validation-test/compiler_crashers_2_fixed/0182-rdar45680857.swift

@@ -0,0 +1,29 @@
+// RUN: %target-swift-frontend -emit-ir %s
+
+public protocol Graph: class, Collection {
+    associatedtype V
+    associatedtype E
+}
+
+public protocol EdgeContainer {
+    associatedtype E
+    associatedtype Visitor: NeighboursVisitor where Visitor.C == Self
+
+    func push(_ thing: E)
+}
+
+public protocol NeighboursVisitor {
+    associatedtype C: EdgeContainer
+    associatedtype G: Graph where G.E == C.E
+}
+
+public enum LIFONeighboursVisitor<C: EdgeContainer, G: Graph>: NeighboursVisitor where G.E == C.E {
+
+}
+
+public class Stack<T, G: Graph>: EdgeContainer where T == G.E {
+    public typealias E = T
+    public typealias Visitor = LIFONeighboursVisitor<Stack<T, G>, G>
+
+    public func push(_ thing: T) {  }
+}