Fix for issue #299 (https://github.com/cbeust/testng/issues/299).

The last chronological-class div in reports/index.html is never closed - leading to a corrupt html file.
Adding an XMLStringBuffer pop() for the last chronological-class panel (if any).

modified:   src/main/java/org/testng/reporters/jq/ChronologicalPanel.java

Previous:
              </div> <!-- configuration-class after -->
          </div> <!-- main-panel-content rounded-window-bottom -->
        </div> <!-- panel -->
      </div> <!-- main-panel-root -->
    </div> <!-- wrapper -->
  </body>
</html>

Current:
              </div> <!-- configuration-class after -->
            </div> <!-- chronological-class -->
          </div> <!-- main-panel-content rounded-window-bottom -->
        </div> <!-- panel -->
      </div> <!-- main-panel-root -->
    </div> <!-- wrapper -->
  </body>
</html>