improved $.browser usage in media panel fix

lib/scripts/media.js

@@ -498,7 +498,7 @@ var dw_mediamanager = {
                 $filePanel.width(relWidthNonResizable+'%');
 
                 // FIXME: please fix without browser sniffing
-                if (jQuery.browser != 'webkit') {
+                if (!jQuery.browser.webkit) {
                     $resizables.each(function() {
                         w = jQuery(this).width();
                         w = (99.99 * w / widthFull);