Compute style-determined compositing reasons during recalc style

Source/core/rendering/compositing/RenderLayerCompositor.cpp

Index: Source/core/rendering/compositing/RenderLayerCompositor.cpp
diff --git a/Source/core/rendering/compositing/RenderLayerCompositor.cpp b/Source/core/rendering/compositing/RenderLayerCompositor.cpp
index 33e71e4bf9be2aa8073bf89161355ce178596998..49e0b1cfba935fcd8a7c6be5ec4bcc7aa9820f48 100644
--- a/Source/core/rendering/compositing/RenderLayerCompositor.cpp
+++ b/Source/core/rendering/compositing/RenderLayerCompositor.cpp
@@ -1569,13 +1569,16 @@ bool RenderLayerCompositor::has3DContent() const
     return layerHas3DContent(rootRenderLayer());
 }
 
-void RenderLayerCompositor::updateDirectCompositingReasons(RenderLayer* layer)
+void RenderLayerCompositor::updateStyleDeterminedCompositingReasons(RenderLayer* layer)
 {
-    CompositingReasons layerReasons = layer->compositingReasons();
+    CompositingReasons reasons = m_compositingReasonFinder.styleDeterminedReasons(layer->renderer());
+    layer->setCompositingReasons(reasons, CompositingReasonComboAllStyleDeterminedReasons);
+}
 
-    layerReasons &= ~CompositingReasonComboAllDirectReasons;
-    layerReasons |= m_compositingReasonFinder.directReasons(layer, &m_needsToRecomputeCompositingRequirements);
-    layer->setCompositingReasons(layerReasons);
+void RenderLayerCompositor::updateDirectCompositingReasons(RenderLayer* layer)
+{
+    CompositingReasons reasons = m_compositingReasonFinder.directReasons(layer, &m_needsToRecomputeCompositingRequirements);
+    layer->setCompositingReasons(reasons, CompositingReasonComboAllDirectReasons);
 }
 
 bool RenderLayerCompositor::needsOwnBacking(const RenderLayer* layer) const