19450 First batch of CanvasKit bindings using @JS (cla: yes)

19451 Roll Skia from d2f870c91102 to b7bfbc299aae (4 revisions) (cla: yes, waiting for tree to go green)

19452 add collection rev variable to DEPS so it gets rolled by the auto roller (cla: yes)

19453 Roll Fuchsia Mac SDK from avEUl… to 4MMwM… (cla: yes, waiting for tree to go green)

19457 Roll Dart SDK from 63feed82e1b1 to 6b4fe2fb78f6 (12 revisions) (cla: yes, waiting for tree to go green)