Fix filename property name for object given to the onCompleted op…

…tion (#157)

Co-authored-by: Sindre Sorhus <sindresorhus@gmail.com>

index.js

@@ -170,7 +170,8 @@ function registerListener(session, options, callback = () => {}) {
 
 				if (typeof options.onCompleted === 'function') {
 					options.onCompleted({
-						fileName: item.getFilename(),
+						fileName: item.getFilename(), // Just for backwards compatibility. TODO: Remove in the next major version.
+						filename: item.getFilename(),
 						path: savePath,
 						fileSize: item.getReceivedBytes(),
 						mimeType: item.getMimeType(),