24801 Update cppwinrt to build 2.0.210304.5 (affects: desktop, cla: yes, platform-windows)

24802 Initialize max_ascent/descent from the strut only if the strut is valid (cla: yes, waiting for tree to go green)

24803 Roll Dart SDK from 1b674d73af53 to 835da00aa6b5 (1 revision) (cla: yes, waiting for tree to go green)

24804 Roll Skia from 6ba242d2a201 to 3b58d38966f4 (1 revision) (cla: yes, waiting for tree to go green)