[web] Migrate framework to fully use package:web (#128901) Remove `dom.dart`'s JS interop definitions in favor of `package:web`. Part of https://github.com/flutter/flutter/issues/113402 Part of https://github.com/flutter/flutter/issues/127030 https://dart.googlesource.com/external/github.com/flutter/flutter/+/bec24367b0e91f4168beed5a55ef2dd17069a6f0