Well... more testing

firefox in safe mode, $x/$y doesn't show , its gone

firefox + noscript with allow scripts scripts globally, $x/$y is gone

firefox + noscript with allow scripts temporarily $x/$y is shown

Nothing obvious in "browser console"

I notice when $x/$y is gone there is syntax hilighting coloring ... so its http://alexgorbatchev.com/SyntaxHighlighter that is responsible

firefox + firebug shows  TypeError: MetaCPAN.storage is null ... and no highlighting is showed

toggling  dom.storage.enabled;false shows the highlighting and $x and $y disappears

I've found mostly spammy junk breaks if localStorage isn't available, anything worth using still works without localStorage

Not going to try to stepping through javascript, I've never found that to be productive, esp with minimized scripts