Fix problem with supporting css pointer-event in IE11 #920

IE-11 supports css pointer-events incorrect:
if your draggable elem contains pseudoelements,
Sortable.js will solve that your draggable elem
are dropping to itself.
So Sortable.js will place your draggable elem to end of list.

This PR let to Sortable.js solve that IE11 doesnt support pointer-events

Sortable.js

@@ -72,6 +72,10 @@
 
 		supportDraggable = !!('draggable' in document.createElement('div')),
 		supportCssPointerEvents = (function (el) {
+			// false when IE11
+			if (!!navigator.userAgent.match(/Trident.*rv[ :]?11\./)) {
+				return false;
+			}
 			el = document.createElement('x');
 			el.style.cssText = 'pointer-events:auto';
 			return el.style.pointerEvents === 'auto';