function updateDebugFolder(folder, isEnabled) {
  if (isEnabled) {
    folder.show();
    folder.open();
  } else {
    folder.hide();
  }
}
Updates the debug folder to be hidden/displayed based on whether the
rendering debugger is enabled.
@param {dat.GUI} folder The folder that holds all the debug
    options.
@param {boolean} isEnabled True if the debugger is enabled, false otherwise.