18475 [fuchsia] Use R8G8B8A8 format instead of B8G8R8A8. (cla: yes)

18476 Roll src/third_party/skia ef3556df44b2..8219e91468d3 (2 commits) (cla: yes, waiting for tree to go green)

18478 Roll src/third_party/skia 8219e91468d3..e7825ff7e34f (3 commits) (cla: yes, waiting for tree to go green)

18479 adding more tests for text form fields (cla: yes)

18480 Fix missing backtick in FlutterViewController docs (cla: yes)

18481 Enable LTO for Fuchsia artifact builds (cla: yes)