This was broken in https://github.com/flutter/flutter/pull/122452. The culprit is that `PipelineOwner.ensureSemantics` doesn't turn on semantics for the entire app, it pretends to only turn it on for the local `PipelineOwner`. Unfortunately, that local `PipelineOwner` is never informed that it should produce semantics when semantics are not turned on globally. So, `PipelineOwner.ensureSemantics` is essentially without effect if semantics are not already turned on globally.
I can't think of a use case where it would be useful to only turn on semantics for a particular pipeline owner and fixing `PipelineOwner.ensureSemantics` would get pretty messy with performance implications even if semantics are turned off. So, this PR deprecates that functionality and moves the `SemanticsDebugger` to the global semantics API.
Fixes https://github.com/flutter/flutter/issues/147665.
26030557b1