Fix bug that`timeDilation` is not reset, causing subsequent test errors, and add verifications to ensure such problem does not exist in the future (#113830)

`Layer ... was previously used as oldLayer` assertion error in debug mode, and page being blank in release mode, caused by LeaderLayer addToScene bug (#113998)

Improves the feel of dragging text selection vertically between lines on mobile.

This reverts commit 103a5c98.

hinText's overflow can now be set via hintStyle (in InputDecoration)