Don't squash images

Since all images added in wikitext get wrapped in a link to the
file page let's restrict the max-width rule to images in links.
This should cover the majority of use cases without impacting
VisualEditor shields

Bug: 62460
Change-Id: I855f9b30b9eecadfe548ab414037cf5f3df086f9
Merge "Don't squash images"