[Layout 2020] Adapt layout viewer to new box and fragment tree structs
[Layout 2020] Adapt layout viewer to new box and fragment tree structs

KiChjang/servo,KiChjang/servo,KiChjang/servo,KiChjang/servo,KiChjang/servo,KiChjang/servo,KiChjang/servo,KiChjang/servo,KiChjang/servo,KiChjang/servo