指示 UnityWebRequest 系统是否应采用 HTTP/1.1 分块传输编码方法。
此属性指示 UnityWebRequest 是否应采用 HTTP/1.1 分块传输编码方法，该方法允许系统发送部分数据，并且由服务器提示系统利用 100/Continue HTTP 响应获取更多数据。调用 Send 后，此属性将无法更改。
In general, this property should usually be set to true, as it can conserve bandwidth when sending large amounts of data to the server. This setting has no impact on requests with do not transmit data to the server, such as GET requests.
Note: On WebGL build targets, this setting is ignored. Instead, the web browser handles protocol negotiations.
Default value: true.