There was a whole team behind Microsoft Trident (IE engine) that was dissolved in favour of third-party (for them) Blink engine. That team was surely knowledgeable, but they had gone.
Blink source is de facto current spec. Each function, if not single line, there is a paragraph in spec.
I remember at WHATWG / HTML5 WG times when Ian Hickson (Google) was pushing whole SQLite (and its SQL flavour) to be included in HTML5 ...
The spec area is so huge and indeed obscure that even Microsoft could not handle it.
Blink source is not the spec, there are W3C specs implemented by Webkit/Blink/Gecko, see the Interop project.
It's not that MS couldn't handle its own engine, it was just not worth it for them in the long term.
Ladybird, NetSurf or Servo engines are prime examples that it is possible to create an independent web engine from scratch even not being a big corp. If they can do it, MS definitely could do it as well if they wanted.
Blink source is de facto current spec. Each function, if not single line, there is a paragraph in spec.
I remember at WHATWG / HTML5 WG times when Ian Hickson (Google) was pushing whole SQLite (and its SQL flavour) to be included in HTML5 ...
The spec area is so huge and indeed obscure that even Microsoft could not handle it.