CompositingReasonFinder should use a virtual function instead of a nest of branches

Source/core/rendering/RenderObject.cpp

Index: Source/core/rendering/RenderObject.cpp
diff --git a/Source/core/rendering/RenderObject.cpp b/Source/core/rendering/RenderObject.cpp
index 82c6a94c70ae77bd2f0b85075f29ad67cb1ab6a6..8808d7d46ff36190bd0e5e5960c87a5ec88903e2 100644
--- a/Source/core/rendering/RenderObject.cpp
+++ b/Source/core/rendering/RenderObject.cpp
@@ -2784,6 +2784,11 @@ CompositingState RenderObject::compositingState() const
     return hasLayer() ? toRenderLayerModelObject(this)->layer()->compositingState() : NotComposited;
 }
 
+CompositingReasons RenderObject::additionalCompositingReasons(CompositingTriggerFlags) const
+{
+    return CompositingReasonNone;
+}
+
 bool RenderObject::acceleratedCompositingForOverflowScrollEnabled() const
 {
     const Settings* settings = document().settings();