RRWeb replayer issue with CSSStyleSheetRule insertion replay

[VladimirMilenko]

I did a couple of tests with styletron CSS in JS library and it appears, that the replay's snapshot functionality is not handling the CSS stylesheetrule insertions correctly when replayed from a certain point.
This seem to be, that snapshot is not correctly handling CSSStyleSheetRule insertion (original issue: #104)

Codesandbox with events and replayer:
https://codesandbox.io/s/trusting-diffie-cwwyq?file=/public/index.html

Replay is available here:
https://user-images.githubusercontent.com/18203255/112888359-8a23ca80-90d4-11eb-832b-3260fd692ff7.mov

[VladimirMilenko]

So, I did some dubigging.
It seems that issue is originating in:

        if (usingVirtualParent && placeholderNode) { // here
          parent.replaceChild(target, placeholderNode);
        }

After replacement, the target's sheet is becoming null. And therefore, the style doesn't apply. I tried to simply remove that code and i can see, that node is containing all styles no matter the start position

[Yuyz0112]

I think this can be closed now:)