Add failing test.

Author: DanielRosenwasser

tests/cases/fourslash/navbarForDoubleAmbientModules01.ts

@@ -0,0 +1,24 @@
+/// <reference path="./fourslash.ts" />
+
+//// declare module "foo";  
+//// declare module "foo";
+
+verify.navigationBar([
+    {
+        "text": "<global>",
+        "kind": "script",
+        "childItems": [
+            {
+                "text": "\"foo\"",
+                "kind": "module",
+                "kindModifiers": "declare"
+            }
+        ]
+    },
+    {
+        "text": "\"foo\"",
+        "kind": "module",
+        "kindModifiers": "declare",
+        "indent": 1
+    }
+]);