[dom] setAttributeNode should not change order of existing attributes (#116)

https://dom.spec.whatwg.org/#concept-element-attributes-set

Per spec, this will remove *oldAttr* and append the new *attr*. This matches Gecko, but not Blink or Edge in this test:
http://software.hixie.ch/utilities/js/live-dom-viewer/saved/3758

Here is the same test using `setAttribute`, where the attribute order does not change:
http://software.hixie.ch/utilities/js/live-dom-viewer/saved/3759

This could be fixed by having the concept of replacing attributes, in addition to append/remove.

CC @bzbarsky @Ms2ger 

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Reply to this email directly or view it on GitHub:
https://github.com/whatwg/dom/issues/116