[Templates] Update FixedController spec

...to reflect changes to how selection object is obtained,
which in turn reflects change to using templates obtained
via RequireJS text plugin, instead of loading by URL.

platform/features/layout/test/FixedControllerSpec.js

@@ -148,6 +148,8 @@ define(
                     mockHandler,
                     mockFormatter
                 );
+
+                findWatch("selection")(mockScope.selection);
             });
 
             it("subscribes when a domain object is available", function () {