Add already-fixed test case from rdar://problem/45557325.

Author: DougGregor

validation-test/compiler_crashers_2_fixed/0180-rdar45557325.swift

@@ -0,0 +1,11 @@
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) %s -typecheck -verify
+
+// REQUIRES: objc_interop
+
+import Foundation
+
+class MyClass: NSObject {
+  func f() {
+    let url = URL(url) // expected-error{{variable used within its own initial value}}
+  }
+}