fix(angular.element): do not break on cleanData() if _data() returns undefined

This shouldn't happen in supported jQuery versions (2+), but if someone
uses the unsupported 1.x version the app will break. The change that
causes this new behavior was introduced in b7d396b.

Even though jQuery 1.x is not supported, it is worth avoiding the
unnecessary breakage (given how simple).

Fixes angular#16641

Closes angular#16642

Author: gkalpak

src/Angular.js

@@ -1909,7 +1909,7 @@ function bindJQuery() {
   jqLite.cleanData = function(elems) {
     var events;
     for (var i = 0, elem; (elem = elems[i]) != null; i++) {
-      events = jqLite._data(elem).events;
+      events = (jqLite._data(elem) || {}).events;
       if (events && events.$destroy) {
         jqLite(elem).triggerHandler('$destroy');
       }

test/jqLiteSpec.js

@@ -501,6 +501,12 @@ describe('jqLite', function() {
       expect(jqLite(c).data('prop')).toBeUndefined();
     });
 
+    it('should not break on cleanData(), if element has no data', function() {
+      var selected = jqLite([a, b, c]);
+      spyOn(jqLite, '_data').and.returnValue(undefined);
+      expect(function() { jqLite.cleanData(selected); }).not.toThrow();
+    });
+
 
     it('should add and remove data on SVGs', function() {
       var svg = jqLite('<svg><rect></rect></svg>');