Fix issue with drag n drop overlay in ie11

web/react/utils/utils.jsx

@@ -1295,5 +1295,9 @@ export function fillArray(value, length) {
 // Checks if a data transfer contains files not text, folders, etc..
 // Slightly modified from http://stackoverflow.com/questions/6848043/how-do-i-detect-a-file-is-being-dragged-rather-than-a-draggable-element-on-my-pa
 export function isFileTransfer(files) {
+    if (isBrowserIE()) {
+        return files.types != null && files.types.contains('Files');
+    }
+
     return files.types != null && (files.types.indexOf ? files.types.indexOf('Files') !== -1 : files.types.contains('application/x-moz-file'));
 }