Bug 1789585 - Replace forward declarations for return type with header includes. r=dom-storage-reviewers,janv

Depends on D163633

Differential Revision: https://phabricator.services.mozilla.com/D163634

dom/fs/parent/FileSystemQuotaClient.h

@@ -7,8 +7,7 @@
 #ifndef DOM_FS_PARENT_FILESYSTEMQUOTACLIENT_H_
 #define DOM_FS_PARENT_FILESYSTEMQUOTACLIENT_H_
 
-template <class T>
-struct already_AddRefed;
+#include "mozilla/AlreadyAddRefed.h"
 
 namespace mozilla::dom {