24208 Roll Skia from 420c8a505e54 to 71d420ddbd3c (3 revisions) (cla: yes, waiting for tree to go green)

24209 Roll Skia from 71d420ddbd3c to 2224100b25e3 (4 revisions) (cla: yes, waiting for tree to go green)

24210 Move shell/platform/common/cpp to shell/platform/common (cla: yes, waiting for tree to go green)

24212 Roll Dart SDK from 51035f288d30 to b1c8ca53bf37 (1 revision) (cla: yes, waiting for tree to go green)