Custom element empty attribute disappears

Hello everyone,

I love custom elements (input, meta, link, etc.) for the freedom it gives to make microdata structures.
However, I was trying to troubleshoot microdata and found what seems to be a bug.

If I leave, an attribute like “itemscope”, “required”, etc. empty, it simply disappears from HTML and breaks the schema:


Here is another where I put quotes (since it looks like that when you leave it empty on other elements):


Here you can see those two custom elements outputs:


Here is a read-only link with just the two custom elements.

Am I missing something?

Thank you very much,