Fix http://issues.umbraco.org/issue/U4-8887

The only usage of __mcenew id is to change the HTML when there is size set on the element. This is done on the timeout function.
As per suggestion - "we wipe the ID in $timeout then, regardless the maxSize"

src/Umbraco.Web.UI.Client/src/common/services/tinymce.service.js

@@ -154,13 +154,13 @@ function tinyMceService(dialogService, $log, imageHelper, $http, $timeout, macro
 
                         var s = "width: " + newSize.width + "px; height:" + newSize.height + "px;";
                         editor.dom.setAttrib(imgElm, 'style', s);
-                        editor.dom.setAttrib(imgElm, 'id', null);
 
                         if (img.url) {
                             var src = img.url + "?width=" + newSize.width + "&height=" + newSize.height;
                             editor.dom.setAttrib(imgElm, 'data-mce-src', src);
                         }
                    }
+                   editor.dom.setAttrib(imgElm, 'id', null);
                }, 500);
             }
         },