Bump flutter_portal to 5584f9bbd5f7dcbc46e3293e395978466c83a453

5584f9bbd5f7dcbc46e3293e395978466c83a453 contains fzyzcjy/flutter_portal#117, which unblocks https://github.com/dart-lang/linter/issues/5063 and https://github.com/dart-lang/linter/issues/5001

Author: srawlins

registry/flutter_portal.test

@@ -1,7 +1,7 @@
 contact=creativecreatorormaybenot@gmail.com
 contact=ch271828n@gmail.com
 fetch=git clone https://github.com/fzyzcjy/flutter_portal.git tests
-fetch=git -C tests checkout 9881d3e8aa729fe0eec67d94f40aaf71fcda678c
+fetch=git -C tests checkout 5584f9bbd5f7dcbc46e3293e395978466c83a453
 update=.
 test=flutter analyze --no-fatal-infos
 test=flutter test