Use shadow DOM for CSS injections about adguardbrowserextension HOT 3 CLOSED

        // Use Shadow DOM if available to don't mess with web pages that rely on
        // the order of their own <style> tags (#309).
        //
        // However, creating a shadow root breaks running CSS transitions. So we
        // have to create the shadow root before transistions might start (#452).
        //
        // Also, using shadow DOM causes issues on some Google websites,
        // including Google Docs and Gmail (#1770, #2602).
        if (document.documentElement && "createShadowRoot" in document.documentElement && !/\.google\.com$/.test(document.domain)) {
            shadow = document.documentElement.createShadowRoot();
            shadow.appendChild(document.createElement("shadow"));
        }

function convertSelectorsForShadowDOM(selectors)
{
  var result = [];
  var prefix = "::content ";

  for (var i = 0; i < selectors.length; i++)
  {
    var selector = selectors[i];
    if (selector.indexOf(",") == -1)
    {
      result.push(prefix + selector);
      continue;
    }

    var start = 0;
    var sep = "";
    for (var j = 0; j < selector.length; j++)
    {
      var chr = selector[j];
      if (chr == "\\")
        j++;
      else if (chr == sep)
        sep = "";
      else if (sep == "")
      {
        if (chr == '"' || chr == "'")
          sep = chr;
        else if (chr == ",")
        {
          result.push(prefix + selector.substring(start, j));
          start = j + 1;
        }
      }
    }

    result.push(prefix + selector.substring(start));
  }

  return result;
}