Fix prompt jumping during reflow
Fix prompt jumping during reflow

If the window is resized while lines are longer than the visible area,
Alacritty will no longer move down the prompt and pull from history when
possible but instead keep the prompt in place and move the additional
lines into the scrollback buffer.

This fixes #2213.
jwilm/alacritty,jwilm/alacritty,jwilm/alacritty,alacritty/alacritty,alacritty/alacritty,jwilm/alacritty