Function updateLineHeight

static/editor.md/lib/codemirror/lib/codemirror.js:7565–7568

(line, height)

  // Update the height of a line, propagating the height change
  // upwards to parent nodes.
  function updateLineHeight(line, height) {
    var diff = height - line.height;
    if (diff) for (var n = line; n; n = n.parent) n.height += diff;
  }

  // Given a line object, find its line number by walking up through
  // its parent links.