62602 Fix doc warnings for focus code (cla: yes, framework)

62614 Make dartdoc warnings fatal for flutter_test (cla: yes, framework, team, waiting for tree to go green)

62615 Fix SliverList scrollOffsetCorrection 0 case (cla: yes, f: scrolling, framework, severe: crash, severe: regression, waiting for tree to go green)

62635 Fixes physics not working when StepperType.horizontal is selected (cla: yes, f: material design, framework, waiting for tree to go green)

62640 promote WidgetTester pumpAndSettle (a: tests, cla: yes, framework, waiting for tree to go green)

62657 Layout paragraph using the appropriate width based on its textWidthBasis (cla: yes, framework)