fix(typeahead): Fix tab index for hint input

Fixes needing to hit tab twice to tab into typeahead with show hint enabled.

Fixes #5478
Closes #5492

Author: deeg

src/typeahead/test/typeahead.spec.js

@@ -1211,6 +1211,11 @@ describe('typeahead tests', function() {
       triggerKeyDown(element, 27);
       expect(hintEl.val()).toEqual('');
     });
+
+    it("should set tab index on hint input element", function(){
+      var hintEl = findInput(element);
+      expect(hintEl.attr('tabindex')).toEqual('-1');
+    });
   });
 
   describe('append to', function() {

src/typeahead/typeahead.js

@@ -129,6 +129,7 @@ angular.module('ui.bootstrap.typeahead', ['ui.bootstrap.debounce', 'ui.bootstrap
       element.after(inputsContainer);
       hintInputElem = element.clone();
       hintInputElem.attr('placeholder', '');
+      hintInputElem.attr('tabindex', '-1');
       hintInputElem.val('');
       hintInputElem.css({
         'position': 'absolute',