--- a/layout/generic/nsContainerFrame.cpp
+++ b/layout/generic/nsContainerFrame.cpp
@@ -1632,17 +1632,16 @@ nsContainerFrame::MoveOverflowToChildLis
   return DrainSelfOverflowList() || result;
 }
 
 bool
 nsContainerFrame::DrainSelfOverflowList()
 {
   AutoFrameListPtr overflowFrames(PresContext(), StealOverflowFrames());
   if (overflowFrames) {
-    NS_ASSERTION(mFrames.NotEmpty(), "overflow list w/o frames");
     mFrames.AppendFrames(nullptr, *overflowFrames);
     return true;
   }
   return false;
 }
 
 nsIFrame*
 nsContainerFrame::GetNextInFlowChild(ContinuationTraversingState& aState,

--- a/layout/generic/nsInlineFrame.cpp
+++ b/layout/generic/nsInlineFrame.cpp
@@ -502,17 +502,16 @@ nsInlineFrame::AttributeChanged(int32_t 
 }
 
 bool
 nsInlineFrame::DrainSelfOverflowListInternal(DrainFlags aFlags,
                                              nsIFrame* aLineContainer)
 {
   AutoFrameListPtr overflowFrames(PresContext(), StealOverflowFrames());
   if (overflowFrames) {
-    NS_ASSERTION(mFrames.NotEmpty(), "overflow list w/o frames");
     // The frames on our own overflowlist may have been pushed by a
     // previous lazilySetParentPointer Reflow so we need to ensure the
     // correct parent pointer.  This is sometimes skipped by Reflow.
     if (!(aFlags & eDontReparentFrames)) {
       nsIFrame* firstChild = overflowFrames->FirstChild();
       if (aLineContainer && aLineContainer->GetPrevContinuation()) {
         ReparentFloatsForInlineChild(aLineContainer, firstChild, true);
       }
@@ -1194,18 +1193,16 @@ nsFirstLineFrame::PullOverflowsFromPrevI
   }
 }
 
 /* virtual */ bool
 nsFirstLineFrame::DrainSelfOverflowList()
 {
   AutoFrameListPtr overflowFrames(PresContext(), StealOverflowFrames());
   if (overflowFrames) {
-    NS_ASSERTION(mFrames.NotEmpty(), "overflow list w/o frames");
-
     bool result = !overflowFrames->IsEmpty();
     const nsFrameList::Slice& newFrames =
       mFrames.AppendFrames(nullptr, *overflowFrames);
     ReparentChildListStyle(PresContext(), newFrames, this);
     return result;
   }
   return false;
 }