11310 When using a custom compositor, ensure the root canvas is flushed. (cla: yes)

11315 Do not add null task observers (cla: yes)

11316 [lsc] Remove fuchsia.net.SocketProvider (cla: yes)

11319 Add tests for platform views (cla: yes)

11322 [fuchsia] Wire up OpacityLayer to Scenic (cla: yes)

11324 Clean up Windows and Linux build output (cla: yes)

11327 [Windows] Update API for alternative Windows shell platform implementation (cla: yes)

11330 Remove engine hash from the output artifact (cla: yes)

11337 Reference the Flutter framework instead of the dylib in iOS tests. (cla: yes)