fix(typeahead): highlight return match if no query

This makes the highlighter behave more consistently like other filters.

It also makes it more useful as an empty query doesn't result in an
empty result.

src/typeahead/test/typeahead-highlight.spec.js

@@ -23,6 +23,12 @@ describe('typeaheadHighlight', function () {
     expect(highlightFilter('before match after', 'nomatch')).toEqual('before match after');
   });
 
+  it('should do nothing if no or empty query', function () {
+    expect(highlightFilter('before match after', '')).toEqual('before match after');
+    expect(highlightFilter('before match after', null)).toEqual('before match after');
+    expect(highlightFilter('before match after', undefined)).toEqual('before match after');
+  });
+
   it('issue 316 - should work correctly for regexp reserved words', function () {
     expect(highlightFilter('before (match after', '(match')).toEqual('before <strong>(match</strong> after');
   });

src/typeahead/typeahead.js

@@ -313,6 +313,6 @@ angular.module('ui.bootstrap.typeahead', ['ui.bootstrap.position'])
     }
 
     return function(matchItem, query) {
-      return query ? matchItem.replace(new RegExp(escapeRegexp(query), 'gi'), '<strong>$&</strong>') : query;
+      return query ? matchItem.replace(new RegExp(escapeRegexp(query), 'gi'), '<strong>$&</strong>') : matchItem;
     };
   });