fix(jqLite): fix memory leaking in IE8 (remove monkey patched methods on Event)

These methods cause IE8 holds the whole jqLite in the memory, even when page is reloaded.
jqLite's cache keeps element's data (event handlers, attached scopes, injector, etc…), so almost all used memory is never released in IE8.

jQuery creates its own Event object (wrapper around native Event) instead.

src/jqLite.js

@@ -514,6 +514,13 @@ forEach({
           forEach(eventHandler.fns, function(fn){
             fn.call(element, event);
           });
+
+          // Remove monkey-patched methods (IE),
+          // as they would cause memory leaks in IE8.
+          // It shouldn't affect normal browsers, as their native methods are defined on prototype.
+          delete event.preventDefault
+          delete event.stopPropagation
+          delete event.isDefaultPrevented
         };
         eventHandler.fns = [];
         addEventListenerFn(element, type, eventHandler);