Fast incremental writer that becomes an ArrayBuffer on end().
class
ArrayBufferSink
class ArrayBufferSink
Flush the internal buffer
If ArrayBufferSink.start was passed a
streamoption, this will return aArrayBufferIf ArrayBufferSink.start was passed astreamoption andasUint8Array, this will return aUint8ArrayOtherwise, this will return the number of bytes written since the last flushThis API might change later to separate Uint8ArraySink and ArrayBufferSink