Revert 157936 "Fix for link highlighting of <img> links"

Caused bad casts on ClusterFuzz.

> Fix for link highlighting of <img> links
> 
> Temporary fix for <img> inside <a>. I changed the node that gets passed to the LinkHighlight object. Previously, when a node was tapped, we'd go up the tree until we find a node that causes a "hand cursor" and use that. Now, we do the same but we stop ascending up the tree if a node isn't contained by its parent's box.
> 
> In the long term, the LinkHighlight should be changed to use the entire hit testing region of the node, rather than the line box.
> 
> BUG=170673
> 
> Review URL: https://chromiumcodereview.appspot.com/24110002

TBR=bokan@chromium.org

Review URL: https://codereview.chromium.org/23707062

git-svn-id: svn://svn.chromium.org/blink/trunk@158080 bbb929c8-8fbe-4397-9dbb-9b2b20218538