--- a/gfx/layers/LayerTreeInvalidation.cpp
+++ b/gfx/layers/LayerTreeInvalidation.cpp
@@ -226,23 +226,23 @@ struct LayerPropertiesBase : public Laye
         AddRegion(result, tmp);
       }
     }
 
     mLayer->ClearInvalidRect();
     return result;
   }
 
-  IntRect NewTransformedBounds()
+  virtual IntRect NewTransformedBounds()
   {
     return TransformRect(mLayer->GetVisibleRegion().ToUnknownRegion().GetBounds(),
                          GetTransformForInvalidation(mLayer));
   }
 
-  IntRect OldTransformedBounds()
+  virtual IntRect OldTransformedBounds()
   {
     return TransformRect(mVisibleRegion.ToUnknownRegion().GetBounds(), mTransform);
   }
 
   virtual nsIntRegion ComputeChangeInternal(NotifySubDocInvalidationFunc aCallback,
                                             bool& aGeometryChanged)
   {
     return IntRect();
@@ -268,18 +268,18 @@ struct ContainerLayerProperties : public
     , mPreXScale(aLayer->GetPreXScale())
     , mPreYScale(aLayer->GetPreYScale())
   {
     for (Layer* child = aLayer->GetFirstChild(); child; child = child->GetNextSibling()) {
       mChildren.AppendElement(Move(CloneLayerTreePropertiesInternal(child)));
     }
   }
 
-  virtual nsIntRegion ComputeChangeInternal(NotifySubDocInvalidationFunc aCallback,
-                                            bool& aGeometryChanged)
+  nsIntRegion ComputeChangeInternal(NotifySubDocInvalidationFunc aCallback,
+                                    bool& aGeometryChanged) override
   {
     ContainerLayer* container = mLayer->AsContainerLayer();
     nsIntRegion invalidOfLayer; // Invalid regions of this layer.
     nsIntRegion result;         // Invliad regions for children only.
 
     bool childrenChanged = false;
 
     if (mPreXScale != container->GetPreXScale() ||
@@ -377,16 +377,41 @@ struct ContainerLayerProperties : public
     }
     // else, effective transforms have applied on children.
 
     result.OrWith(invalidOfLayer);
 
     return result;
   }
 
+  IntRect NewTransformedBounds() override
+  {
+    if (mLayer->Extend3DContext()) {
+      IntRect result;
+      for (UniquePtr<LayerPropertiesBase>& child : mChildren) {
+        result = result.Union(child->NewTransformedBounds());
+      }
+      return result;
+    }
+
+    return LayerPropertiesBase::NewTransformedBounds();
+  }
+
+  IntRect OldTransformedBounds() override
+  {
+    if (mLayer->Extend3DContext()) {
+      IntRect result;
+      for (UniquePtr<LayerPropertiesBase>& child : mChildren) {
+        result = result.Union(child->OldTransformedBounds());
+      }
+      return result;
+    }
+    return LayerPropertiesBase::OldTransformedBounds();
+  }
+
   // The old list of children:
   AutoTArray<UniquePtr<LayerPropertiesBase>,1> mChildren;
   float mPreXScale;
   float mPreYScale;
 };
 
 struct ColorLayerProperties : public LayerPropertiesBase
 {