Add regression test for rdar 36305791 (already fixed)

Author: Nathan Hawes

test/SourceKit/CursorInfo/rdar_36305791.swift

@@ -0,0 +1,8 @@
+public class Observable<Element> {
+  public typealias E = Element
+}
+Observable.create { }
+
+// RUN: %sourcekitd-test -req=cursor -cursor-action -pos=4:12 -length 10 %s -- %s | %FileCheck %s
+
+// CHECK: source.lang.swift.ref.module ()