Quite strange issue. If page: * url ends with # * contains iframe with position: fixed style * iframe content was filled with iframe.contentDocument.open and close the scroll will glitch at the bottom of the page. Chromium 24 here.
Created attachment 187549 [details] proof, add # at the end
after you've opened an attachement, push CTRL+R.
reproduced in Canary 26.01
That's quite an effect! Affects Safari 6.0.3 and current build too.
Isn't reproduced anymore in Chrome 27.
Chrome has branched WebKit. This is still reproducible with mainline WebKit (tested current build with Safari on Mac).
In Safari 8 the page is still scrolled to the bottom, but scroll isn't locked there.
It's working fine in Safari 10.1