28675 [web] clear surfaces on hot restart (cla: yes, platform-web, needs tests)

28683 fuchsia: Use buffer_collection_x extension (cla: yes, platform-fuchsia, needs tests)

28694 Do not share the GrDirectContext across engine instances on Android (platform-android, cla: yes, waiting for tree to go green, needs tests)

28698 Wrap ImageShader::sk_image_ with a SkiaGPUObject (cla: yes, waiting for tree to go green, needs tests)

28707 Fix duplicated documentation (cla: yes, waiting for tree to go green, needs tests)

28724 [UWP] Add modifier keys support (cla: yes, platform-windows, needs tests)

28734 [fuchsia] Fix missing function in V2 dart runner. (cla: yes, platform-fuchsia, needs tests)