fix WebFile flow type

flow-typed/web-file.js

@@ -1,7 +1,6 @@
-declare type WebFile = {
-  name: string,
+// @flow
+
+declare type WebFile = File & {
+  path?: string,
   title?: string,
-  path: string,
-  size: string,
-  type: string,
 }

ui/component/publishFile/view.jsx

@@ -241,6 +241,7 @@ function PublishFile(props: Props) {
     }
   }
 
+  // Flow error [+]
   function handleFileChange(file: WebFile) {
     const { showToast } = props;
     window.URL = window.URL || window.webkitURL;