16651 Roll fuchsia/sdk/core/mac-amd64 from FS4mm… to PGe1A… (cla: yes, waiting for tree to go green)

16652 Roll fuchsia/sdk/core/linux-amd64 from m7Xt4… to Uc8XS… (cla: yes, waiting for tree to go green)

16653 Lift restriction that embedders may not trample the render thread OpenGL context in composition callbacks. (cla: yes)

16655 Roll src/third_party/skia 3c4f3c178ade..9dbb98007b7b (2 commits) (cla: yes, waiting for tree to go green)

16656 Roll src/third_party/skia 9dbb98007b7b..4af17e434cdc (2 commits) (cla: yes, waiting for tree to go green)