Mouse: better check for not IE9 or greater in case mode was set by X-…

…UA-Compatible. See http://msdn.microsoft.com/en-us/library/cc196988%28VS.85%29.aspx for more info. Fixes #5370 - All drag & drop events fail in IE9. Thanks xirzec.

ui/jquery.ui.mouse.js

@@ -93,7 +93,7 @@ $.widget("ui.mouse", {
 
 	_mouseMove: function(event) {
 		// IE mouseup check - mouseup happened when mouse was out of window
-		if ($.browser.msie && parseInt($.browser.version, 10) < 9 && !event.button) {
+		if ($.browser.msie && !(document.documentMode >= 9) && !event.button) {
 			return this._mouseUp(event);
 		}