The test is turning out to be quite difficult to implement. If I try to implement the
repro situation locally via <object> elements transitioning from display:none to display:
inline, loading the SVG will result in the callsite to UpdateStyleAndLayoutTree in
Document::FinishedParsing, because CommittedFirstRealDocumentLoad was true.
In the real site, this is false, for whatever reason related to quirks of loading.

Adding a unittest is challenging, but should be a more feasible way forward.

It is just way to hard to do this.