I think this function can probably be switched to use nsComputedDOMStyle::GetStyleContextNoFlush() to avoid a style flush. This means that it could be using relatively stale style information, which is currently probably an issue given where this is called <https://searchfox.org/mozilla-central/rev/ae94cfb36d804727dfb38f2750bfcaab4621df6e/editor/libeditor/HTMLEditorObjectResizer.cpp#92>, but some testing may be needed. It may be a good idea to somehow move this to happen after the style flush that happens as part of the refresh driver tick.

That is by bug 47066...

mozilla::HTMLEditor::GetAbsolutelyPositionedSelectionContainer checks whether current element has position:aboslute. But does it require computedstyle?

We probably could just move CheckSelectionStateForAnonymousButtons to be called around tick time. Less hacky than use possibly stale position information.

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