20865 Add auto plugin registration to FlutterFragmentActivity as well (cla: yes, platform-android)

20869 Reset Shell::weak_factory_gpu_ on the raster thread (cla: yes, waiting for tree to go green)

20871 lerpDouble: stricter handling of NaN and infinity (cla: yes)

20874 Extract Dart test utilities library (cla: yes)

20879 Improve the precision of lerpDouble (cla: yes)

20880 Add integer input tests for lerpDouble (cla: yes)

20895 Enable lazy-async-stacks by-default in all modes (Take 3) (cla: yes)

20899 Member variables should appear before the

WeakPtrFactory

. (cla: yes)