23693 Roll Fuchsia Mac SDK from BoBy7Eobf… to DVYrV15dq… (cla: yes, waiting for tree to go green)

23694 Ensure gen_snapshot for the target is built when needed (cla: yes, waiting for tree to go green)

23696 [web] Reland: Enable the new rich paragraph implementation (cla: yes, platform-web)

23698 Roll buildroot to 92a8d2eb7aad592068f808e39b8330fd2bce25e3, Clang to 12.0.0 (cla: yes)

23699 Roll Dart SDK from 3629a798353d to a461c2b3366d (1 revision) (cla: yes, waiting for tree to go green)