25057 Import gtest_util.h and DispatchStub from upstream Chromium (cla: yes)

25058 Complete Picture.toImage futures with an exception if the image is null (cla: yes, waiting for tree to go green)

25064 Decode empty message to nil in standard codec (affects: desktop, cla: yes, crash, platform-ios, platform-macos)

25077 Add config for “Linux Fuchsia FEMU” try builder. (cla: yes)

25078 Convert format and lint scripts to null safety. (cla: yes, waiting for tree to go green)

25080 [web] Fix handling of ClipOp.none (cla: yes, platform-web)

25088 [web] Implement font features in the html renderer (cla: yes, platform-web)