activeBackend property
Null, and stated rather than inherited: on web the runtime picks the
accelerator itself and the answer does not exist until the first
embedding, so a synchronous getter cannot carry it. The JS side reports it
— window.getLiteRtEmbeddingAccelerator() and
getLiteRtEmbeddingFullyAccelerated(). Saying so here keeps "we cannot
know" distinguishable from "nobody thought about it", which a default
alone cannot.
Implementation
@override
PreferredBackend? get activeBackend => null;