fix(storage, web): fix UploadTask by fixing TaskEvent Web Interop (#9212)

Author: Lyokone

packages/firebase_storage/firebase_storage_web/lib/src/interop/storage.dart

@@ -333,10 +333,11 @@ class UploadTask extends JsObjectWrapper<storage_interop.UploadTaskJsImpl> {
 
     void startListen() {
       onStateChangedUnsubscribe = jsObject.on(
-          storage_interop.TaskEvent.STATE_CHANGED,
-          nextWrapper,
-          errorWrapper,
-          onCompletion);
+        storage_interop.TaskEvent,
+        nextWrapper,
+        errorWrapper,
+        onCompletion,
+      );
     }
 
     void stopListen() {

packages/firebase_storage/firebase_storage_web/lib/src/interop/storage_interop.dart

@@ -229,11 +229,4 @@ class StringFormat {
   external static String get DATA_URL;
 }
 
-// ignore: avoid_classes_with_only_static_members
-/// An event that is triggered on a task.
-///
-/// See: <https://firebase.google.com/docs/reference/js/firebase.storage#.TaskEvent>.
-@JS()
-abstract class TaskEvent {
-  external static String get STATE_CHANGED;
-}
+external String get TaskEvent;