Add /** @deferred */ comments to deferred callback parameters

[ahejlsberg]

This PR adds /** @deferred */ comments to deferred callback parameters in preparation for microsoft/TypeScript#58729.

[github-actions]

Thanks for the PR!

This section of the codebase is owned by @saschanaz - if they write a comment saying "LGTM" then it will be merged.

[saschanaz]

You also need to npm run build && npm run baseline-accept.

[saschanaz]

(Looks good. feel free to merge when the TS PR is ready)

[saschanaz]

One question, why not use deferred modifier when we are using TypeScript here? (Edit: Oh, for backward compat, cool.)

[saschanaz]

And another question, is it the requirement here for the callback to be called asynchronously? What happens if those callbacks can be called both sync/async?

[ahejlsberg]

And another question, is it the requirement here for the callback to be called asynchronously?

The deferred modifier (and the /** @deferred */ JSDoc comment) asserts that the callback is never called synchronously. If a synchronous call is a possibility, then the parameter shouldn't have the modifier.

BTW, I haven't been able to find any authoritative documentation on sync vs. async for the various DOM callbacks, so it could well be that some of the modifiers shouldn't be present.