change dom3 core to not throw WRONG_DOCUMENT_ERR

WebKit is changing to match Gecko and not throw WRONG_DOCUMENT_ERR in a
number of cases.

https://bugs.webkit.org/show_bug.cgi?id=19524

Is there an editor for http://www.w3.org/TR/DOM-Level-3-Core/? These
cross-document restrictions cause an unnecessary burden on web developers
and soon WebKit and Gecko will not be firing them. Is there any possibility
of changing the spec to match?

Ojan