message: [terminal] Grid: Fixes VT sequence SD (yay).
diff: @@ -489,9 +489,8 @@ void Grid<Cell>::scrollDown(LineCount v_n,
  // move all lines up by N lines
  // bottom N lines are wiped out
  - auto const marginHeight = LineCount(_margin.vertical.length());
  - std::rotate(
  - std::begin(mainPage()), std::next(begin(mainPage()), *marginHeight - *n), std::end(mainPage()));
  + rotateBuffersRight(n);
  +
  for (Line<Cell>& line: mainPage().subspan(0, *n))
  line.reset(defaultLineFlags(), _defaultAttributes);
  return;
  