Right now, WebKit puts "length" property of NodeList on the object itself. This doesn't match either DOM4 specification (http://www.w3.org/TR/2014/CR-dom-20140508/#interface-nodelist) or Firefox 29's behavior.
sadness. fixable, but sadness :(
I thought this might be a side effect of us having names properties on NodeList but then ordinary named properties don't override attributes in the object's prototype so we should be able to fix it right away.
*** This bug has been marked as a duplicate of bug 154051 ***