* Add warning if rendering and HTMLUnknownElement
* Records fiber tests
* Fixes linting and server render tests
* Incorporates review comments
* Uses ownerDocument instead of document
* uses el instead of creating a new element
* Removes warning check of voidElementTags
* Add missing space to unknown element warning
* Only call isCustomComponent once
* Spy on console in menuitem test
Since menuitem is treated as an unknown element in jsdom it triggers the unknown element warning.
* Add unknown element warning to Fiber
* Replace instanceof with toString check
It is more resilient.
* Record tests
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