The visitLinksForShortLinks feature would look inside of an <a> tag and
run shortLinkProcessorFull on any text, which attempts to create links
out of potential 'short links' like [[test]] [[link|example]] etc...
This makes no sense because you can't have nested links within an <a>
tag. Specifically, the html5 standard says <a> tags can't include
interactive content if they contain the href attribute:
http://w3c.github.io/html/single-page.html#the-a-element
And also defines an <a> element with a href attribute as interactive:
http://w3c.github.io/html/single-page.html#interactive-content
Therefore you can't really put a link inside of another link. In
practice none of this works anyways since browsers won't render it, it
would probably be broken if they tried, and it is causing a bug
(#4946). No current tests rely on this behavior either.
This removes the feature and also explicitly excludes the
current visitNodeForShortLinks from looking in <a> tags.
020075e12f