stream: reject writes during WritableStream close - #67058

WritableStreamDefaultControllerProcessClose clears the controller algorithms while the stream is still 'writable', before the sink close settles. A write in that window reaches the cleared size algorithm and fails the internal assertion in writableStreamDefaultControllerGetChunkSize, which crashes the process instead of rejecting the write:

const ws = new WritableStream({ close() { return new Promise(() => {}); } });
const writer = ws.getWriter();
writer.close();
setImmediate(() => writer.write('x'));
// Error [ERR_INTERNAL_ASSERTION]: This is caused by either a bug in Node.js ...

The same happens when writing to a TransformStream whose flush() is pending. This affects v26.5.1 as well as main.

#57280 handled the 'closed' case (#57272, whatwg/streams#1341). The spec still asserts that the state is not 'writable' there, so the close-in-flight window is a gap in the spec too. This also accepts that state, so the write continues to the closing check and is rejected with a TypeError, as it is once the stream has closed.

Tests are added to test-whatwg-writablestream-close.js for both cases; they fail with the assertion on main.

Refs: #57272
Refs: whatwg/streams#1341

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