26209 Add more diagrams for deferred components docs, fix alignment of existing one (cla: yes)

26210 Capture the layer tree pipeline as a weak pointer in the OnAnimatorDraw task (cla: yes, waiting for tree to go green)

26212 Roll Dart SDK from 67be110b5ba8 to 510f26486328 (3 revisions) (cla: yes, waiting for tree to go green)

26213 Roll Skia from 2fed9f62d29a to e8cd0a54041e (2 revisions) (cla: yes, waiting for tree to go green)

26215 Adds package:litetest, uses it instead of package:test under testing/dart (cla: yes)