Cloning nodes using XQUF upper-cases the name of HTML elements

[bwrrp]

The native HTML DOM has the quirky behavior of upper-casing the nodeName property of any element in the HTML namespace. Unfortunately, by default FontoXPath uses the nodeName in order to clone elements (see https://github.com/FontoXML/fontoxpath/blob/master/src/domClone/deepCloneNode.ts#L42). The result is that when run against a DOM implementation that follows this behavior, such as the native DOM in browsers, cloned nodes unintentionally have their localName and (if applicable) prefix upper-cased relative to their originals.

Consider the following example, ran against the XPath playground with e aliased to evaluateUpdatingExpression (using a temporary breakpoint):

(await e('//*:fds-state-message', document.documentElement)).xdmValue[0].localName
> "fds-state-message" 

(await e('<div>{//*:fds-state-message}</div>', document.documentElement)).xdmValue[0].firstChild.localName
> "FDS-STATE-MESSAGE" 

I think the easiest way to avoid this would be to re-implement the nodeName construction ourselves in DomFacade#getNodeName (https://github.com/FontoXML/fontoxpath/blob/master/src/domFacade/DomFacade.ts#L244), at least for element nodes, by combining the node's prefix (if present) with its localName.