* Alert dialog dartpad demo

* Updated description

In each library where an import is removed, the library uses some elements
provided by the import, BUT there is another import which provides all of the
same elements, and at least one more which the library uses.

In this change, we remove the imports which can be simply removed in favor of
the other already present imports.

See https://github.com/dart-lang/sdk/issues/44569 for more information.

TextField and last input character should visible on the screen when the cursor is not shown (#74722)

This fixes a subtle bug in the focus traversal that would leave unfocusable FocusTraversalGroup nodes in the list of sorted nodes to be traversed, causing an assert to fire if you nested a FocusTraversalGroup in another one and made its children unfocusable.