Per a discussion in Discord, running flutter build bundle as part of a custom embedding build flow is apparently getting (at least in debug mode) the Dart plugin registration generated. This breaks the intent that the registration is embedding-specific, driven by the embedding-specific dartPluginClass entries in the pubspec.

This will be problematic for custom embeddings expecting the default platform channel--including existing implementations that used to work--as we move to diverging per-package platform channels.