Empty prefix and url namespace inserted for basic root element

[drott]

For a basic document source without DOCTYPE or xml processing instruction, an extra "":"" entry is added to namespaces.

<root xmlns:foo="http://www.example.com" attr="test2" foo:attr="test" />

Expected namespaces in StartElement event:

{
 "foo": "http://www.example.com", 
 "xml": "http://www.w3.org/XML/1998/namespace", 
 "xmlns": "http://www.w3.org/2000/xmlns/"
}

Actual namespaces:

{
 "": "", 
 "foo": "http://www.example.com", 
 "xml": "http://www.w3.org/XML/1998/namespace", 
 "xmlns": "http://www.w3.org/2000/xmlns/"
}

Test case in:
https://github.com/drott/xml-rs/blob/emptyNsForRoot/tests/streaming.rs#L122

[drott]

Similarly, extra empty NSgenerated for a Chromium test in:
virtual/rust-xml/fast/xmlhttprequest/xmlhttprequest-get.xhtml

[drott]

Closing this, I interpret this to mean that the "" : "" entry means: The default namespace is empty, which I don't think is wrong in the namespace list. Chromium's problem in using the xml crate remains the issue in #48 - so, at the root element, for example, we cannot tell whether in the source text there is an explicit xmlns="" in the source document or not.