This reverts commit 17870d5d.

This reverts commit 9b56241e.

This reverts commit 1f0df545.

Adds MediaQuery.maybeOf to replace calling MediaQuery.of(context, nullOk: true), and removes the nullOk parameter. Also changes MediaQuery.of to return a non-nullable value, and removes many instances of the ! operator, reducing the possible places where a null dereference could occur.

This migrates more material tests to NNBD.

* adds titleSpacing in AppBarTheme
Co-authored-by: Shi-Hao Hong <shihaohong@google.com>

Reland "Prevent viewport.showOnScreen from scrolling the viewport if the specified Rect is already visible. (#56413)" reverted in #64091 (#64513)

Revert "Prevent viewport.showOnScreen from scrolling the viewport if the specified Rect is already visible.  (#56413)" (#64091)

This reverts commit 64d76f2f.

Prevent viewport.showOnScreen from scrolling the viewport if the specified Rect is already visible.  (#56413)

Updated references to the old button classes to the new ones in comments and documentation for tests in the material and cupertino libraries. (#62164)

This reverts commit 1e843bb6.