Bug 2033191 made sure we only call ownerGlobal on nodes.
As per the discussion in dev-platform, the front-end ~always wants
.documentGlobal. This removes ownerGlobal from the bindings. Following
patch will rename internal GetOwnerGlobal in gecko to GetRelevantGlobal
as per the HTML spec terminology.
Differential Revision: https://phabricator.services.mozilla.com/D297183