Pasting labels sometimes adds a Div element that is not present in the source of the copy

[BryanValverdeU]

Describe the bug
Div is added under label on paste, should not happen

To Reproduce
Steps to reproduce the behavior:

1. Go to 'https://codepen.io/Bryanvalverdeu/pen/zYXOobZ
2. copy content
3. paste in ROosterJS Content model demo
4. See that the label elements have a Div Wrapped causing the labels to have 2 lines

Expected behavior
Div should not be added

[JiuqingSong]

I think the problem is not adding DIV, but "display:flex", which is not supported in our code.

I feel this result is by design. Unless we want to support flex.

[BryanValverdeU]

Not sure, in the source content, in the Label we do not have a div inside of the element:

Once it is pasted a div is appended to the label:

If I remove the inner Div in the label, the extra spacing is gone:

Do you feel this is by design or a fidelity issue?

[JiuqingSong]

1. There is "display:flex" which is something we don't support.
2. The HTML element "label" is not handled today. I think we can just treat it as a regular segment then this should be fixed

[JiuqingSong]

I tried to add label with knownElementProcessor, then no additional DIV is added: