Support AbortSignal.throwIfAborted()

[DLiblik]

Part of the spec and very useful in looping procedural code:

// somewhere inside some func that takes a signal
for(const item of items) {
  signal?.throwIfAborted();
  // part 1 of expensive per-item code here...
  signal?.throwIfAborted();
  // part 2 of expensive per-item code here...
}

[onestep]

I would also ask to add support for reason property to support passing custom exceptions to abort signal.

[onestep]

Example implementation in nodejs - https://github.com/nodejs/node/pull/40951/files.

[benlesh]

Sorry for the ridiculously late review. This is a good add, but a little incorrect. The problem is it has to throw whatever was passed to abort() on the abort controller. Which is super weird, but there it is.