code: function _onLoadEventFired(event, res) {
          // res = {timestamp}
          Inspector.DOM.getDocument(function onGetDocument(res) {
              exports.trigger("getDocument", res);
              // res = {root}
              _idToNode = {};
              _pendingRequests = 0;
              exports.root = new DOMNode(exports, res.root);
          });
      }
docs: WebInspector Event: Page.loadEventFired