20348 [iOS TextInput] Fixes selection clamping & composing range change logic (cla: yes, platform-ios)

20349 CanvasKit: memory management for image and shader classes (cla: yes)

20350 Prepare scenario app to run on Android emulator on LUCI  (cla: yes)

20357 Fix flutter#40068 Redraw issues on resize/minimize/maximize on Windows and startup in release (cla: yes, waiting for tree to go green)

20370 Paragraph.longest_line_ to account for trailing inline placeholders (cla: yes)

20379 Fix nullability warning and change registeredFonts to non-nullable (cla: yes)

20380 remove FrameTiming named constructor (cla: yes, waiting for tree to go green)