[whatwg/streams] Pure Pull doesn't seem to work through TransformStream? (Issue #1354)

MeirionHughes created an issue (whatwg/streams#1354)

### What is the issue with the Streams Standard?

I'm investigating an oddity and wondered if it was a node issue, but it seems (unless I'm doing something wrong) it's in the reference implementation too. 

I'm testing the scenario where you put the stream completely into pull-only mode, by making everything have a hightwaterMark of 0, EXCEPT the ultimate sink. The sink (or reader) initiates the pulling to get the data flowing 1 item at a time. 

This works for ReadableStream, but not through the TransformStream. For transformStream I have to make the readableStrategy 1, which presumably acts as a sink for the upstream source and allows it to flow. 

Sure - this isn't how you want to use streams, but I find it odd it doesn't seem to work in pure pull mode and TransformStreams have to buffer at least 1 item. 

So my question is, does the standard allow for pure pull (from sink) to pull through TransformStreams?

My test that shows it hangs trying to do this: 

```ts
globalThis.window = globalThis;
globalThis.gc = global.gc
delete globalThis.TransformStream
try{ new TransformStream(); } catch(err){  
  console.log("deleted node's TransformStream"); 
}

require("./reference/reference-implementation/lib/index.js")

let timer;

async function main() {
  let strategy = new CountQueuingStrategy({ highWaterMark: 0 });
  let srcGen = () => {
    let counter = 0;
    return new ReadableStream({
      pull(controller) {
        controller.enqueue(counter++);
        if (counter > 3)
          controller.close();
      }
    }, strategy);
  };
  
  // ReadableStream only 0-buffer

  let result1 = [];
  let src1 = srcGen();
  let reader1 = src1.getReader();

  while (true) {
    let { value, done } = await reader1.read();
    if (done) break; result1.push(value);
  }

  console.log("src1 results", result1);

  // ReadableStream > Transform 0-buffer

  let src2 = srcGen().pipeThrough(new TransformStream({}, strategy /* set to {highwaterMark:1} and it works */, strategy));
  let result2 = [];

  let reader2 = src2.getReader();

  while (true) {
    let { value, done } = await reader2.read();
    if (done) break;
    result2.push(value);
  }

  console.log("src2 results", result2);

  if (timer) clearTimeout(timer);
}

timer = setTimeout(() => {
  console.log("timed out");
  process.exit(1);
}, 3000)

main().catch(console.error);

```
```shell

> node check.cjs --expose-gc 
deleted node's TransformStream
src1 results [ 0, 1, 2, 3 ]
timed out
```







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