类：ReadableStreamDefaultController

¥Class: ReadableStreamDefaultController

每个 <ReadableStream> 都有一个控制器，负责流队列的内部状态和管理。ReadableStreamDefaultController 是 ReadableStream 的默认控制器实现，它不是面向字节的。

¥Every <ReadableStream> has a controller that is responsible for the internal state and management of the stream's queue. The ReadableStreamDefaultController is the default controller implementation for ReadableStreams that are not byte-oriented.