function pollWebKit() {
    var css = pending.css, i;

    if (css) {
      i = styleSheets.length;

      // Look for a stylesheet matching the pending URL.
      while (--i >= 0) {
        if (styleSheets[i].href === css.urls[0]) {
          finish('css');
          break;
        }
      }

      pollCount += 1;

      if (css) {
        if (pollCount < 200) {
          setTimeout(pollWebKit, 50);
        } else {
          // We've been polling for 10 seconds and nothing's happened, which may
          // indicate that the stylesheet has been removed from the document
          // before it had a chance to load. Stop polling and finish the pending
          // request to prevent blocking further requests.
          finish('css');
        }
      }
    }
  }
Begins polling to determine when pending stylesheets have finished loading
  in WebKit. Polling stops when all pending stylesheets have loaded or after 10
  seconds (to prevent stalls).

  @method pollWebKit
  @private