fix(autocomplete): always hide the progressbar when clearing the input

Fixes #8301, #8195.

Closes #8341

Author: crisbeto

src/components/autocomplete/js/autocompleteController.js

@@ -780,6 +780,7 @@ function MdAutocompleteCtrl ($scope, $element, $mdUtil, $mdConstant, $mdTheming,
     if (!$scope.noCache && cache[ term ]) {
       ctrl.matches = cache[ term ];
       updateMessages();
+      setLoading(false);
     } else {
       fetchResults(searchText);
     }