Use case

The BackgroundIsolateBinaryMessenger API requires an ensureInitialized() method call before its instance field can be used. Unfortunately the web implementation of the BackgroundIsolateBinaryMessenger does not have the ensureInitialized() method, to the compilation targeted for the web is failing at compile time with Member not found: 'BackgroundIsolateBinaryMessenger.ensureInitialized' error.

Currently we have to make own wrapper with platform-specific import to make this compile on web.

Proposal

It would be really handy if BackgroundIsolateBinaryMessenger has consistent API between io and web implementations. It will be sufficient to have it throw UnsupportedError('Isolates not supported on web.')