diff --git a/gfx/thebes/PrintTarget.cpp b/gfx/thebes/PrintTarget.cpp
index a077513003..900cbd81a0 100644
--- a/gfx/thebes/PrintTarget.cpp
+++ b/gfx/thebes/PrintTarget.cpp
@@ -58,7 +58,7 @@ PrintTarget::MakeDrawTarget(const IntSize& aSize,
 
   // This should not be called outside of BeginPage()/EndPage() calls since
   // some backends can only provide a valid DrawTarget at that time.
-  MOZ_ASSERT(mHasActivePage, "We can't guarantee a valid DrawTarget");
+  NS_WARNING_ASSERTION(mHasActivePage, "We can't guarantee a valid DrawTarget without an active page. Content may be missing.");
 
   if (cairo_surface_status(mCairoSurface)) {
     return nullptr;
diff --git a/layout/tables/nsTableFrame.h b/layout/tables/nsTableFrame.h
index 7fcdcb9d87..f843ae9a8b 100644
--- a/layout/tables/nsTableFrame.h
+++ b/layout/tables/nsTableFrame.h
@@ -81,9 +81,6 @@ class nsDisplayTableBackgroundSet {
   nsDisplayTableBackgroundSet(nsDisplayListBuilder* aBuilder, nsIFrame* aTable)
       : mBuilder(aBuilder) {
     mPrevTableBackgroundSet = mBuilder->SetTableBackgroundSet(this);
-    mozilla::DebugOnly<const nsIFrame*> reference =
-        mBuilder->FindReferenceFrameFor(aTable, &mToReferenceFrame);
-    MOZ_ASSERT(nsLayoutUtils::IsAncestorFrameCrossDoc(reference, aTable));
     mDirtyRect = mBuilder->GetDirtyRect();
   }