[cgiow] (3) Change how dir='' works, from being an embedding to being an override, for better results on mixed-directionality sites. THIS IS A HIGH RISK CHANGE, EXPECT BREAKAGE. Please report breakage on the bug if it's higher than acceptable, so we can revert the change if necessary.
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=23260
Affected topics: HTML, Rendering

git-svn-id: http://svn.whatwg.org/webapps@8283 340c8d12-0b0e-0410-8428-c7bf67bfef74
(cherry picked from commit a43f5fb21c05c159be980c9567bcaa59a49308f1)