Web updates

Streams a3e482279576

Add state checks to Close() and Enqueue() (#1029) Exit early from abstract operations ReadableStreamDefaultControllerClose() and ReadableStreamDefaultControllerEnqueue() if ReadableStreamDefaultControllerCanCloseOrEnqueue() is false. Remove the asserts that it is true, and the requirement that callers perform the check as part of the interface contract. In practice the implementation of ReadableStreamTee() was failing to properly check CanCloseOrEnqueue(). By relaxing the interface contract we can prevent similar problems with future standards. Also remove a now-redundant check of CanCloseOrEnqueue() in TransformStreamDefaultControllerTerminate(). Also make similar changes to ReadableByteStreamControllerClose() and ReadableByteStreamControllerEnqueue().

Adam Rice