22687 fuchsia: Ensure full-screen input interceptor (cla: yes, platform-fuchsia)

22690 Roll Dart SDK from 962ef010aedd to cde050a4c0b4 (2 revisions) (cla: yes, waiting for tree to go green)

22692 Let FlutterFragment not pop the whole activity by default when more fragments are in the activity (cla: yes, platform-android, waiting for tree to go green)

22704 Roll Fuchsia Linux SDK from Nmo4pkY2s… to GlHwWVGTU… (cla: yes, waiting for tree to go green)

22707 Roll Fuchsia Mac SDK from qC9Z6PMoY… to QKCl4nBGL… (cla: yes, waiting for tree to go green)