45749 Fix buildCounter returns a widget when set to return null. (cla: yes, f: material design, framework)

45750 Remove canTransitionFrom override from Material/CupertinoPageRoute (cla: yes, f: cupertino, f: material design, framework)

45786 prevent VsCode from crashing on malformed packages.json file (cla: yes, tool)

45787 implicit-casts:false in dev (a: accessibility, cla: yes, f: material design, team)

45805 implicit-casts:false in examples (cla: yes, d: examples, f: cupertino, f: material design, team, team: gallery)

45817 Roll engine 6c605f8a9624..8672e79af873 (2 commits) (autoroller: commit, cla: yes)