TextEvent 构造函数
实现
factory TextEvent(String type,
{bool canBubble = false,
bool cancelable = false,
Window? view,
String? data}) {
if (view == null) {
view = window;
}
TextEvent e = document._createEvent("TextEvent") as TextEvent;
e._initTextEvent(type, canBubble, cancelable, view, data);
return e;
}