diff --git a/layout/painting/FrameLayerBuilder.h b/layout/painting/FrameLayerBuilder.h
--- a/layout/painting/FrameLayerBuilder.h
+++ b/layout/painting/FrameLayerBuilder.h
@@ -273,16 +273,20 @@ struct ContainerLayerParameters {
     , mScrollMetadataASR(aParent.mScrollMetadataASR)
     , mCompositorASR(aParent.mCompositorASR)
     , mInTransformedSubtree(aParent.mInTransformedSubtree)
     , mInActiveTransformedSubtree(aParent.mInActiveTransformedSubtree)
     , mDisableSubpixelAntialiasingInDescendants(aParent.mDisableSubpixelAntialiasingInDescendants)
     , mForEventsAndPluginsOnly(aParent.mForEventsAndPluginsOnly)
     , mLayerCreationHint(aParent.mLayerCreationHint)
   {}
+  bool Scaled() {
+    return (0x3f800000 != *(uint32_t *)&mXScale) ||
+           (0x3f800000 != *(uint32_t *)&mYScale);
+  }
 
   float mXScale, mYScale;
 
   LayoutDeviceToLayerScale2D Scale() const {
     return LayoutDeviceToLayerScale2D(mXScale, mYScale);
   }
 
   /**
