attr: [object Attr]
attr.ownerElement: [object HTMLDivElement]
attr.namespaceURI: null
attr.localName: foo
attr.name: foo
attr.value: bar
attr.specified: true

clone: [object Attr]
clone.ownerElement: null
clone.namespaceURI: null
clone.localName: foo
clone.name: foo
clone.value: bar
clone.specified: true

attr === clone -> false
attr.isEqualNode(clone) -> true
attr.isEqualNode(other) -> false