[meta] Auto open menu (and close other) doesn't work in Firefox 36+

[Infocatcher]

&& node.namespaceURI == xulns
&& node.boxObject
&& node.boxObject instanceof Components.interfaces.nsIMenuBoxObject // Always false now

Probably due to https://bugzilla.mozilla.org/show_bug.cgi?id=979835 - Port BoxObject to WebIDL.

[Infocatcher]

Oh, downloads button have open property (from chrome://global/content/bindings/button.xml#button-base), but that property only sets attribute (and don't open/close downloads panel).

[Infocatcher]

Also check for node.boxObject presence should be removed for Firefox 69+…