--- a/layout/painting/FrameLayerBuilder.cpp
+++ b/layout/painting/FrameLayerBuilder.cpp
@@ -1793,33 +1793,24 @@ FrameLayerBuilder::FlashPaint(gfxContext
 {
   float r = float(rand()) / RAND_MAX;
   float g = float(rand()) / RAND_MAX;
   float b = float(rand()) / RAND_MAX;
   aContext->SetColor(Color(r, g, b, 0.4f));
   aContext->Paint();
 }
 
-static FrameLayerBuilder::DisplayItemData*
-AssertDisplayItemData(FrameLayerBuilder::DisplayItemData* aData)
-{
-  MOZ_RELEASE_ASSERT(aData);
-  MOZ_RELEASE_ASSERT(sAliveDisplayItemDatas && sAliveDisplayItemDatas->Contains(aData));
-  MOZ_RELEASE_ASSERT(aData->mLayer);
-  return aData;
-}
-
 FrameLayerBuilder::DisplayItemData*
 FrameLayerBuilder::GetDisplayItemData(nsIFrame* aFrame, uint32_t aKey)
 {
   const nsTArray<DisplayItemData*>* array =
     aFrame->Properties().Get(LayerManagerDataProperty());
   if (array) {
     for (uint32_t i = 0; i < array->Length(); i++) {
-      DisplayItemData* item = AssertDisplayItemData(array->ElementAt(i));
+      DisplayItemData* item = array->ElementAt(i);
       if (item->mDisplayItemKey == aKey &&
           item->mLayer->Manager() == mRetainingManager) {
         return item;
       }
     }
   }
   return nullptr;
 }
@@ -2038,34 +2029,34 @@ FrameLayerBuilder::WillEndTransaction()
 /* static */ FrameLayerBuilder::DisplayItemData*
 FrameLayerBuilder::GetDisplayItemDataForManager(nsDisplayItem* aItem,
                                                 LayerManager* aManager)
 {
   const nsTArray<DisplayItemData*>* array =
     aItem->Frame()->Properties().Get(LayerManagerDataProperty());
   if (array) {
     for (uint32_t i = 0; i < array->Length(); i++) {
-      DisplayItemData* item = AssertDisplayItemData(array->ElementAt(i));
+      DisplayItemData* item = array->ElementAt(i);
       if (item->mDisplayItemKey == aItem->GetPerFrameKey() &&
           item->mLayer->Manager() == aManager) {
         return item;
       }
     }
   }
   return nullptr;
 }
 
 bool
 FrameLayerBuilder::HasRetainedDataFor(nsIFrame* aFrame, uint32_t aDisplayItemKey)
 {
   const nsTArray<DisplayItemData*>* array =
     aFrame->Properties().Get(LayerManagerDataProperty());
   if (array) {
     for (uint32_t i = 0; i < array->Length(); i++) {
-      if (AssertDisplayItemData(array->ElementAt(i))->mDisplayItemKey == aDisplayItemKey) {
+      if (array->ElementAt(i)->mDisplayItemKey == aDisplayItemKey) {
         return true;
       }
     }
   }
   return false;
 }
 
 void
@@ -2073,17 +2064,17 @@ FrameLayerBuilder::IterateRetainedDataFo
 {
   const nsTArray<DisplayItemData*>* array =
     aFrame->Properties().Get(LayerManagerDataProperty());
   if (!array) {
     return;
   }
 
   for (uint32_t i = 0; i < array->Length(); i++) {
-    DisplayItemData* data = AssertDisplayItemData(array->ElementAt(i));
+    DisplayItemData* data = array->ElementAt(i);
     if (data->mDisplayItemKey != nsDisplayItem::TYPE_ZERO) {
       aCallback(aFrame, data);
     }
   }
 }
 
 FrameLayerBuilder::DisplayItemData*
 FrameLayerBuilder::GetOldLayerForFrame(nsIFrame* aFrame, uint32_t aDisplayItemKey)
@@ -2141,17 +2132,17 @@ FrameLayerBuilder::GetDebugOldLayerFor(n
   const nsTArray<DisplayItemData*>* array =
     aFrame->Properties().Get(LayerManagerDataProperty());
 
   if (!array) {
     return nullptr;
   }
 
   for (uint32_t i = 0; i < array->Length(); i++) {
-    DisplayItemData *data = AssertDisplayItemData(array->ElementAt(i));
+    DisplayItemData *data = array->ElementAt(i);
 
     if (data->mDisplayItemKey == aDisplayItemKey) {
       return data->mLayer;
     }
   }
   return nullptr;
 }
 
@@ -2162,17 +2153,16 @@ FrameLayerBuilder::GetDebugSingleOldPain
     aFrame->Properties().Get(LayerManagerDataProperty());
 
   if (!array) {
     return nullptr;
   }
 
   Layer* layer = nullptr;
   for (DisplayItemData* data : *array) {
-    AssertDisplayItemData(data);
     if (!data->mLayer->AsPaintedLayer()) {
       continue;
     }
     if (layer && layer != data->mLayer) {
       // More than one layer assigned, bail.
       return nullptr;
     }
     layer = data->mLayer;
@@ -5788,34 +5778,34 @@ FrameLayerBuilder::InvalidateAllLayers(L
 
 /* static */ void
 FrameLayerBuilder::InvalidateAllLayersForFrame(nsIFrame *aFrame)
 {
   const nsTArray<DisplayItemData*>* array =
     aFrame->Properties().Get(LayerManagerDataProperty());
   if (array) {
     for (uint32_t i = 0; i < array->Length(); i++) {
-      AssertDisplayItemData(array->ElementAt(i))->mParent->mInvalidateAllLayers = true;
+      array->ElementAt(i)->mParent->mInvalidateAllLayers = true;
     }
   }
 }
 
 /* static */
 Layer*
 FrameLayerBuilder::GetDedicatedLayer(nsIFrame* aFrame, uint32_t aDisplayItemKey)
 {
   //TODO: This isn't completely correct, since a frame could exist as a layer
   // in the normal widget manager, and as a different layer (or no layer)
   // in the secondary manager
 
   const nsTArray<DisplayItemData*>* array =
     aFrame->Properties().Get(LayerManagerDataProperty());
   if (array) {
     for (uint32_t i = 0; i < array->Length(); i++) {
-      DisplayItemData *element = AssertDisplayItemData(array->ElementAt(i));
+      DisplayItemData *element = array->ElementAt(i);
       if (!element->mParent->mLayerManager->IsWidgetLayerManager()) {
         continue;
       }
       if (element->mDisplayItemKey == aDisplayItemKey) {
         if (element->mOptLayer) {
           return element->mOptLayer;
         }
 
@@ -5864,17 +5854,17 @@ FrameLayerBuilder::GetPaintedLayerScaleF
 
     const nsTArray<DisplayItemData*>* array =
       f->Properties().Get(LayerManagerDataProperty());
     if (!array) {
       continue;
     }
 
     for (uint32_t i = 0; i < array->Length(); i++) {
-      Layer* layer = AssertDisplayItemData(array->ElementAt(i))->mLayer;
+      Layer* layer = array->ElementAt(i)->mLayer;
       ContainerLayer* container = layer->AsContainerLayer();
       if (!container ||
           !layer->Manager()->IsWidgetLayerManager()) {
         continue;
       }
       for (Layer* l = container->GetFirstChild(); l; l = l->GetNextSibling()) {
         PaintedDisplayItemLayerUserData* data =
             static_cast<PaintedDisplayItemLayerUserData*>
@@ -6304,17 +6294,17 @@ FrameLayerBuilder::GetMostRecentGeometry
     properties.Get(LayerManagerDataProperty());
   if (!dataArray) {
     return nullptr;
   }
 
   // Find our display item data, if it exists, and return its geometry.
   uint32_t itemPerFrameKey = aItem->GetPerFrameKey();
   for (uint32_t i = 0; i < dataArray->Length(); i++) {
-    DisplayItemData* data = AssertDisplayItemData(dataArray->ElementAt(i));
+    DisplayItemData* data = dataArray->ElementAt(i);
     if (data->GetDisplayItemKey() == itemPerFrameKey) {
       return data->GetGeometry();
     }
   }
 
   return nullptr;
 }