Severity: wishlist

eww-follow-link currently follows #target links in the same URL by
re-rendering the page.  Whilst this is fine for small HTML files, the
1.9M HTML file that I'm currently visiting takes a couple seconds to
render.
I see that eww-display-html follows #target links by a text property
search, why don't we do the same in eww-follow-link as well?  I have one
question though: what do we about non-existent #targets?  Chrome and
Firefox seem to not scroll when I add a non-existent #target to the
current URL and say RET, and it seems to specially handle #top to mean
to go to the top even if the HTML has no hits for "#top".  Should we
handle the special #top target?
By non-existent targets, I mean to say that

    (goto-char (point-min))
    (text-property-search-forward 'shr-target-id "invalid" #'member)

returns nil for a non-existent "#invalid" target.

Tentative patch attached,