17716 Updates to use predefined keys. (cla: yes)

17717 Remove franciscojma86 from autoassign (cla: yes)

17718 System mouse cursor: Web (cla: yes)

17726 Roll fuchsia/sdk/core/mac-amd64 from X4B0z… to dqerH… (cla: yes, waiting for tree to go green)

17727 Roll src/third_party/skia 44e2c5f0babc..e6995c74cdfa (12 commits) (cla: yes, waiting for tree to go green)

17729 Release acquired typed data before calling Dart_SetReturnValue. (cla: yes, waiting for tree to go green)