AbortSignal.any: Mark dependent abort signals as aborted before firing events

[shaseley]

Spec PR: whatwg/dom#1295

[avivkeller]

See https://whatpr.org/dom/1295/7c494e5...0d05525.html for the diff

CC @nodejs/web-standards

[avivkeller]

The resolution of this issue will make Node.js's AbortController and AbortSignal complaint with WPT.