--- a/layout/style/ImageLoader.cpp
+++ b/layout/style/ImageLoader.cpp
@@ -428,18 +428,18 @@ ImageLoader::OnSizeAvailable(imgIRequest
 {
   nsPresContext* presContext = GetPresContext();
   if (!presContext) {
     return NS_OK;
   }
 
   aImage->SetAnimationMode(presContext->ImageAnimationMode());
 
-  FrameSet* frameSet = nullptr;
-  if (!mRequestToFrameMap.Get(aRequest, &frameSet)) {
+  FrameSet* frameSet = mRequestToFrameMap.Get(aRequest);
+  if (!frameSet) {
     return NS_OK;
   }
 
   for (nsIFrame* frame : *frameSet) {
     if (frame->StyleVisibility()->IsVisible()) {
       frame->MarkNeedsDisplayItemRebuild();
     }
   }
@@ -449,18 +449,18 @@ ImageLoader::OnSizeAvailable(imgIRequest
 
 nsresult
 ImageLoader::OnImageIsAnimated(imgIRequest* aRequest)
 {
   if (!mDocument) {
     return NS_OK;
   }
 
-  FrameSet* frameSet = nullptr;
-  if (!mRequestToFrameMap.Get(aRequest, &frameSet)) {
+  FrameSet* frameSet = mRequestToFrameMap.Get(aRequest);
+  if (!frameSet) {
     return NS_OK;
   }
 
   // Register with the refresh driver now that we are aware that
   // we are animated.
   nsPresContext* presContext = GetPresContext();
   if (presContext) {
     nsLayoutUtils::RegisterImageRequest(presContext,
@@ -473,45 +473,41 @@ ImageLoader::OnImageIsAnimated(imgIReque
 
 nsresult
 ImageLoader::OnFrameComplete(imgIRequest* aRequest)
 {
   if (!mDocument || mInClone) {
     return NS_OK;
   }
 
-  FrameSet* frameSet = nullptr;
-  if (!mRequestToFrameMap.Get(aRequest, &frameSet)) {
+  FrameSet* frameSet = mRequestToFrameMap.Get(aRequest);
+  if (!frameSet) {
     return NS_OK;
   }
 
-  NS_ASSERTION(frameSet, "This should never be null!");
-
   // Since we just finished decoding a frame, we always want to paint, in case
   // we're now able to paint an image that we couldn't paint before (and hence
   // that we don't have retained data for).
   DoRedraw(frameSet, /* aForcePaint = */ true);
 
   return NS_OK;
 }
 
 nsresult
 ImageLoader::OnFrameUpdate(imgIRequest* aRequest)
 {
   if (!mDocument || mInClone) {
     return NS_OK;
   }
 
-  FrameSet* frameSet = nullptr;
-  if (!mRequestToFrameMap.Get(aRequest, &frameSet)) {
+  FrameSet* frameSet = mRequestToFrameMap.Get(aRequest);
+  if (!frameSet) {
     return NS_OK;
   }
 
-  NS_ASSERTION(frameSet, "This should never be null!");
-
   DoRedraw(frameSet, /* aForcePaint = */ false);
 
   return NS_OK;
 }
 
 void
 ImageLoader::FlushUseCounters()
 {