--- a/layout/base/nsDisplayList.cpp
+++ b/layout/base/nsDisplayList.cpp
@@ -1777,17 +1777,17 @@ already_AddRefed<LayerManager> nsDisplay
   }
 
   if (widgetTransaction) {
     layerBuilder->DidBeginRetainedLayerTransaction(layerManager);
   }
 
   nsIFrame* frame = aBuilder->RootReferenceFrame();
   nsPresContext* presContext = frame->PresContext();
-  nsIPresShell* presShell = presContext->GetPresShell();
+  nsIPresShell* presShell = presContext->PresShell();
   nsRootPresContext* rootPresContext = presContext->GetRootPresContext();
 
   NotifySubDocInvalidationFunc computeInvalidFunc =
     presContext->MayHavePaintEventListenerInSubDocument() ? nsPresContext::NotifySubDocInvalidation : 0;
   bool computeInvalidRect = (computeInvalidFunc ||
                              (!layerManager->IsCompositingCheap() && layerManager->NeedsWidgetInvalidation())) &&
                             widgetTransaction;
 
@@ -1804,20 +1804,17 @@ already_AddRefed<LayerManager> nsDisplay
   }
 
   ContainerLayerParameters containerParameters
     (presShell->GetResolution(), presShell->GetResolution());
   RefPtr<ContainerLayer> root = layerBuilder->
     BuildContainerLayerFor(aBuilder, layerManager, frame, nullptr, this,
                            containerParameters, nullptr);
 
-  nsIDocument* document = nullptr;
-  if (presShell) {
-    document = presShell->GetDocument();
-  }
+  nsIDocument* document = presShell->GetDocument();
 
   if (!root) {
     layerManager->SetUserData(&gLayerManagerLayerBuilder, oldBuilder);
     return nullptr;
   }
   // Root is being scaled up by the X/Y resolution. Scale it back down.
   root->SetPostScale(1.0f/containerParameters.mXScale,
                      1.0f/containerParameters.mYScale);