A `:has()` left of `+` in editor.css made Chromium restyle every element
under .tiptap on each inserted child, so the band-clearing rule keys on a
data-wrap-band attribute the imageLine plugin writes. getLineRects reuses
one Range instead of leaving hundreds alive. TipTap's Placeholder, which
hit-tested the viewport on every keystroke, is replaced by placeholder.ts.
docPosBeforeElement is memoised per pass. At 124 pages the pass after a
split drops from 410 to 150 ms and the split keystroke from 219 to 50 ms.
Steffen Becker
5db1c37468