fix(autocomplete): addresses issue where dropdown shows if there is an initial value

Closes #2517

Author: Robert Messerle

src/components/autocomplete/js/autocompleteController.js

@@ -190,8 +190,8 @@ function MdAutocompleteCtrl ($scope, $element, $mdUtil, $mdConstant, $timeout, $
 
   function handleSearchText (searchText, previousSearchText) {
     self.index = getDefaultIndex();
-    //-- do nothing on init if there is no initial value
-    if (!searchText && searchText === previousSearchText) return;
+    //-- do nothing on init
+    if (searchText === previousSearchText) return;
     //-- clear selected item if search text no longer matches it
     if (searchText !== getDisplayValue($scope.selectedItem)) $scope.selectedItem = null;
     else return;