push method
将新页面压入堆栈。
Implementation
void push(Route route, Element element, Route? previousRoute) {
final page = Page(route, element);
QTTrackLogger.i(this.toString(), page);
QTTrackLogger.i(this.toString(), {'func:', "push", 'page:', page});
_stack.add(page);
// final prePage = _findPreviousPage(previousRoute);
_task.addPush(page, page.previous);
}