we could use just string.split, but IE doesn't like returning empty strings
function split_linebreaks(s) {
  //return s.split(/\x0d\x0a|\x0a/);

  s = s.replace(acorn.allLineBreaks, '\n');
  var out = [],
    idx = s.indexOf("\n");
  while (idx !== -1) {
    out.push(s.substring(0, idx));
    s = s.substring(idx + 1);
    idx = s.indexOf("\n");
  }
  if (s.length) {
    out.push(s);
  }
  return out;
}