This avoids a high cost which appears to be the system rasterizing the
cursor every time we call this, fixes a slowdown when scrolling rapidly
while mouse motion continually attempted to assign the style

Fixes
https://linear.app/zed-industries/issue/Z-2200/editor-scroll-slowdown

Release Notes:

- Improved the performance of scrolling by avoiding unnecessary cursor
changes
([#1597](https://github.com/zed-industries/community/issues/1597)).