Add a UseCounter for Element.setAttributeNodeNS

This function was also removed from DOM4, it must have been overlooked
when the other UseCounters were added.

BUG=325922

Review URL: https://codereview.chromium.org/107093007

git-svn-id: svn://svn.chromium.org/blink/trunk@163363 bbb929c8-8fbe-4397-9dbb-9b2b20218538