Bug 1614432 - Remove redundant nested #IF r=dholbert

Differential Revision: https://phabricator.services.mozilla.com/D62529

--HG--
extra : moz-landing-system : lando

layout/generic/nsGridContainerFrame.cpp

@@ -8429,13 +8429,11 @@ void nsGridContainerFrame::StoreUsedTrackSizes(
 #ifdef DEBUG
 void nsGridContainerFrame::SetInitialChildList(ChildListID aListID,
                                                nsFrameList& aChildList) {
-#  ifdef DEBUG
   ChildListIDs supportedLists = {kAbsoluteList, kFixedList, kPrincipalList};
   // We don't handle the kBackdropList frames in any way, but it only contains
   // a placeholder for ::backdrop which is OK to not reflow (for now anyway).
   supportedLists += kBackdropList;
   MOZ_ASSERT(supportedLists.contains(aListID), "unexpected child list");
-#  endif
 
   return nsContainerFrame::SetInitialChildList(aListID, aChildList);
 }