1. Go to acko.net 2. find main resource, go to DOM content view 3. Turn on compositing borders. Yay, borders. 4. Drag the inspector window. Boo, borders disappear. You have to re-enable the borders button to get them back on the page.
Weird! Related to that scriptsEnabled thing?
As far as I can tell, it's not triggered by settings changes (like https://webkit.org/b/130147).
<rdar://problem/28228561>