code: function _onFinishedLoadingDOM() {
          var request = new XMLHttpRequest();
          request.open("GET", exports.url);
          request.onload = function onLoad() {
              if ((request.status >= 200 && request.status < 300) ||
                      request.status === 304 || request.status === 0) {
                  _mapDocumentToSource(request.response);
                  _load.resolve();
              } else {
                  var msg = "Received status " + request.status + " from XMLHttpRequest while attempting to load source file at " + exports.url;
                  _load.reject(msg, { message: msg });
              }
          };
          request.onerror = function onError() {
              var msg = "Could not load source file at " + exports.url;
              _load.reject(msg, { message: msg });
          };
          request.send(null);
      }
docs: Load the source document and match it with the DOM tree