This requires all AnimationController objects to be given a
TickerProvider, a class that can create the Ticker.
It also provides some nice mixins for people who want to have their
State provide a TickerProvider. And a schedulerTickerProvider for those
cases where you just want to see your battery burn.
Also, we now enforce destruction order for elements.
This rewrites imports of various mojom.dart files from the Flutter
engine repo to instead import normal-looking dart files from the
(new) flutter_services package. This package handles exporting the
correct symbols from generated code wherever that may live.
Includes an engine roll to 3551e7a48e2e336777b15c7637af92fd7605b6c5
which contains the new flutter_services package.
The 'routes' table is a point of confusion with new developers. By
providing a 'home' argument that sets the '/' route, we can delay the
point at which we teach developers about 'routes' until the point where
they want to have a second route.
Most of the remaining widget examples are actually manual tests. This patch
moves them into //dev/manual_tests. A couple are examples of using services,
which I've moved to //examples/layers/services. The remainder are out-dated and
are removed by this patch.
