In the beginning of Element::removeAttributeNode() we check that attr object
passed to it belongs to the same element (comparing attr.GetElement and this).
If it is different element, throw NotFoundError.
Mochitest to check new behavior included.
--HG--
extra : rebase_source : 8582d119a99d23d121ad9f7fe5b184668641bf80
Boris Egorov