1. https://rp-online.de/nrw/staedte/duisburg/
2. Assertion failure: mFrameWillChangeBudgets.Contains(aFrame) Nightly on Fedora 30 at least.

Assertion failure: mFrameWillChangeBudgets.Contains(aFrame), at /builds/worker/workspace/build/src/layout/painting/nsDisplayList.cpp:2507
#01: nsDisplayListBuilder::IsInWillChangeBudget(nsIFrame*, nsSize const&) 
#02: mozilla::ScrollFrameHelper::IsScrollingActive(nsDisplayListBuilder*) const 
#03: nsDisplayListBuilder::IsAnimatedGeometryRoot(nsIFrame*, bool&, nsIFrame**) 
#04: nsDisplayListBuilder::FindAnimatedGeometryRootFrameFor(nsIFrame*, bool&) 
#05: nsDisplayListBuilder::FindAnimatedGeometryRootFor(nsIFrame*) 
#06: RetainedDisplayListBuilder::ProcessFrame(nsIFrame*, nsDisplayListBuilder*, nsIFrame*, nsTArray<nsIFrame*>&, bool, nsRect*, AnimatedGeometryRoot**) 
#07: RetainedDisplayListBuilder::ComputeRebuildRegion(nsTArray<nsIFrame*>&, nsRect*, AnimatedGeometryRoot**, nsTArray<nsIFrame*>&) 
#08: RetainedDisplayListBuilder::AttemptPartialUpdate(unsigned int, mozilla::DisplayListChecker*) 
#09: nsLayoutUtils::PaintFrame(gfxContext*, nsIFrame*, nsRegion const&, unsigned int, nsDisplayListBuilderMode, nsLayoutUtils::PaintFrameFlags) 
#10: mozilla::PresShell::Paint(nsView*, nsRegion const&, mozilla::PaintFlags) 

regression range

This test case requires full-screen-api.allow-trusted-requests-only=false

This assertion is harmless and quite difficult to get rid of without introducing unnecessary complexity.

I had a chat with Matt about this and will-change budgeting in general, and we came to the conclusion that in the long run we might even consider deleting the whole budget. It was initially added to avoid abuse of will-change property, but AFAIK there has not been any real world use-cases of this.

https://hg.mozilla.org/mozilla-central/rev/b4f592ebb7ec