fix: Set localName as part of Document.createElement

[rrthomas]

This seemed to be missing. Without it, xpath (XPath 1.0) works, but
xpath2 (XPath 2.0) and fontoxpath (XPath 3.x) do not match elements.

[karfau]

I just checked, the property Element.localName (and also setting that value as part of Document.createElement) is only specified in the DOM living standard, but Node.localName is already specified in DOM Level 2.

I also checked that we are already and in all cases setting this field as part of Document.createElementNS (so using that method instead could be a workaround, until this PR is merged and released.

@rrthomas Thank you for the PR, are you able to add some minimal test(s) to test/dom/element.test.js that make sure this doesn't break again? (You can add a nested describe with a message of "createElement" and add your tests to it.)

[rrthomas]

Thanks for the analysis (I'm not an expert in this area, so didn't venture to go further on my own!). I'll see if I can add a test.

[karfau]

Thank you for your contribution, it will be part of the next release.