fix(datepicker): change to $popup

Author: wesleycho

Diff for: src/datepicker/datepicker.js

@@ -595,7 +595,7 @@ function($compile, $parse, $document, $rootScope, $position, dateFilter, datePar
           delete options.initDate;
         }
         angular.forEach(options, function(value, option) {
-          datepickerEl.attr( cameltoDash(option), value );
+          datepickerEl.attr(cameltoDash(option), value);
         });
       }
 
@@ -715,7 +715,7 @@ function($compile, $parse, $document, $rootScope, $position, dateFilter, datePar
       });
 
       var documentClickBind = function(event) {
-        if (scope.isOpen && !(element[0].contains(event.target) || popupEl[0].contains(event.target))) {
+        if (scope.isOpen && !(element[0].contains(event.target) || $popup[0].contains(event.target))) {
           scope.$apply(function() {
             scope.isOpen = false;
           });