1837472 - Fix XML serialization to serialize implicit xmlns attributes first and use lowercase “ns” when generating prefixes

Status: NEW

(Core :: XML, defect)

Description

[Thomas Wisniewski [:twisniewski]]

WebKit recently aligned with Blink on some cases in https://bugs.webkit.org/show_bug.cgi?id=248747 , where they now match on some tests in the WPT
https://wpt.fyi/results/domparsing/XMLSerializer-serializeToString.html?label=experimental&label=master&aligned

The changes made to achieve that are listed as:

• Serialize xmlns attributes before we serialize the attribute they are for
• Use lowercase "ns" in the generated namespace prefix

It's unknown if this has any real webcompat impact, but it would be good to align on these WPTs just in case.