12982 Color matrix doc (cla: yes)

12983 Roll Wuffs to 0.2.0-rc.1 (cla: yes)

12986 Prevent default when Tab is clicked (accessibility, affects: text input, cla: yes, platform-web)

12987 Added FlutterActivity and FlutterFragment hook to cleanUpFlutterEngine() as symmetry for configureFlutterEngine(). (#41943) (cla: yes)

12988 Use the standard gen_snapshot target unless the platform requires host_targeting_host (cla: yes)

12989 Unpublicize kDoNotResizeDimension (cla: yes)

12990 Fix for a11y crash on iOS (cla: yes)

12991 Compile sanitizer suppressions list and file bugs as necessary. (cla: yes)