Ms2ger

I think this could benefit from review at this point

I noticed it in #10104, but I would be surprised if that was the only offender

I guess so, but you have conflicts to resolve

Still conflicts

Please add copyright and frontmatter: https://github.com/tc39/test262/blob/main/CONTRIBUTING.md#test-case-style On what basis did you decide which implementation was correct?

> > If the attribute works (and I don't see why it wouldn't), we should prefer it over further manual adjustments to the "create a namespace object" algorithm. You'll need...

Exactly: https://github.com/servo/string-cache/issues/26

I understood that @jgraham wanted to take another look at this

Please use `.tentative.` in the file names

That's certainly the first issue, yes.