Fixes#155552
For lists, the outer ul/ol always has the same source line as the first element in the list. We should prefer using the first element in the list when highlighting the active line
This also fixes a bug where scroll sync would stop working if you added lines to the doc. This was caused by `lineCount` getting out of sync as the document is being updated. I've removed this state and made the reveal logic more robust instead
* Fix scrolling of markdown preview.
* Use scrollDisabledCount.
* Stop initializing scrollDisabledCount.
* Make scrollTo enough large to occur scroll events.
* Should resolve when the error event occurs.
