Consider moving "retargeting" to the dispatch section

[annevk]

@hayatoito are there other specifications that need to use "retargeting" for some reason or is this solely for events? (Currently the definition is exported, but it seems to me that might no longer be necessary.)

[hayatoito]

AFAIK, "retargeting" is referred from several other standards:

• https://fullscreen.spec.whatwg.org/

Other than that, I don't recall which standard, but I remember I recently commented on a PR which tries to use retargeting, as fullscreen does, in other standards.

[annevk]

Thanks, I'll add a note to the retargeting algorithm about such usage so I don't forget.