Hack around Parsoid's href prefixing in rendering new links

If we render new links with a plain target, then if you're on a
subpage like Foo/Bar, [[Baz]] will point to Foo/Baz. In order to
avoid this, we fake the link target to be ../Baz and resolve that,
which produces the correct result.

This hack is only needed until Parsoid stops producing ../-prefixed
links. This hack is only applied in view mode, because applying
it to our DOM output back to Parsoid would confuse Parsoid and
cause bugs.

Bug: 58314
Change-Id: Ifb4b63a26235a04e6362fc3e3e57d8773831eb38
Merge "Hack around Parsoid's href prefixing in rendering new links"