44611 Convert to TextPosition for getWordBoundary

44617 Make disposing a ScrollPosition with pixels=null legal

44622 Track and use fallback TextAffinity for null affinity platform TextSelections.

44967 Try a mildly prettier FlutterError and make it less drastic in release mode

45083 Fix draggable scrollable sheet scroll notification

45240 implicit-casts:false in flutter_web_plugins

45249 implicit-casts:false in flutter_goldens and flutter_goldens_client

Engine

In this update, the core engine continues to see many improvements, including a fix that solves the long-requested scrolling performance issue on iPhoneX/Xs.

9386 [glfw] Send the glfw key data to the framework.