If an element in a named flow thread has no offsetParent inside the named flow, its offsetParent will be the document's body (http://dev.w3.org/csswg/css-regions/#cssomview-offset-attributes). In this situation, the offsetLeft and offsetTop values are not correctly computed.
Related to https://bugs.webkit.org/show_bug.cgi?id=113276
Created attachment 202277 [details] Patch
Comment on attachment 202277 [details] Patch r=me
Comment on attachment 202277 [details] Patch Clearing flags on attachment: 202277 Committed r150383: <http://trac.webkit.org/changeset/150383>
All reviewed patches have been landed. Closing bug.