Dart and other libraries used by Flutter

The Dart language itself has a separate breaking-change policy,
with announcements on Dart announce.

In general, the Flutter team does not currently have any commitment
regarding breaking changes for other dependencies. For example,
it’s possible that a new version of Flutter using a new version of Skia
(the graphics engine used by Flutter) or Harfbuzz (the font shaping
engine used by Flutter) would have changes that affect contributed
tests. Such changes would not necessarily be accompanied by a
migration guide.