27564 Fix window bug in _sendPlatformMessage() (#27541). (cla: yes, framework, p: framework)

27566 Warn when gradle builds fail because of AndroidX (cla: yes, t: gradle, tool)

27568 Fix initial scroll of TabBar in release mode (cla: yes, f: material design, f: scrolling, framework)

27569 Bugfix: Add platformBrightness to TestWindow. (a: tests, cla: yes)

27570 Small cleanup in CupertinoSliverRefreshControl (cla: yes, f: cupertino, framework)

27573 Let text selection toolbar buttons be independent from theme (cla: yes, f: cupertino, framework)

27575 Update OutlineButton default border width and highlight elevation (cla: yes, f: material design, framework)