They're being overwritten by default arguments when the page loads.
Internal PR #163767, this is a regression due to the fix for bug #87817
Created attachment 146271 [details]
Comment on attachment 146271 [details]
Clearing flags on attachment: 146271
Committed r119721: <http://trac.webkit.org/changeset/119721>
All reviewed patches have been landed. Closing bug.