It seems that setTraversalBefore doesn't work as well as setTraversalAfter for some reason, although I'm using them the same way. Some apps would lock up TalkBack when traversing if setTraversalBefore was set, but not with the equivalent setTraversalAfter.
It's not entirely clear why this is, but I'm going with this to at least get it fixed for apps we know about.
Addresses flutter/flutter#14600
See also flutter/flutter#14607
This adds support for semantics traversal ordering.
It is a companion to flutter/flutter#14060, adding support for a sortIndex in the semantics data passed to the engine.
Addresses flutter/flutter#12187
This patch prepares us to switch sending semantics information over mojom to
using dart:ui directly. Currently the recorded information is dropped on the
floor, but that will improve in future patches.
