Refactor to simplify how layerType is stored on PaintLayers.

third_party/WebKit/Source/core/paint/PaintLayer.h

Index: third_party/WebKit/Source/core/paint/PaintLayer.h
diff --git a/third_party/WebKit/Source/core/paint/PaintLayer.h b/third_party/WebKit/Source/core/paint/PaintLayer.h
index b190197cf90abb94029d6366dba38807390cc17e..a1ef52b116f07206562d01346ca1320261660232 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayer.h
+++ b/third_party/WebKit/Source/core/paint/PaintLayer.h
@@ -209,7 +209,7 @@ struct PaintLayerRareData {
 class CORE_EXPORT PaintLayer : public DisplayItemClient {
     WTF_MAKE_NONCOPYABLE(PaintLayer);
 public:
-    PaintLayer(LayoutBoxModelObject*, PaintLayerType);
+    PaintLayer(LayoutBoxModelObject*);
     ~PaintLayer() override;
 
     // DisplayItemClient methods
@@ -239,8 +239,6 @@ public:
     // FIXME: Many people call this function while it has out-of-date information.
     bool isSelfPaintingLayer() const { return m_isSelfPaintingLayer; }
 
-    void setLayerType(PaintLayerType layerType) { m_layerType = layerType; ASSERT(static_cast<PaintLayerType>(m_layerType) == layerType); }
-
     bool isTransparent() const { return layoutObject()->isTransparent() || layoutObject()->style()->hasBlendMode() || layoutObject()->hasMask(); }
 
     bool isReflection() const { return layoutObject()->isReplica(); }
@@ -786,8 +784,6 @@ private:
         m_needsPaintPhaseDescendantBlockBackgrounds |= layer.m_needsPaintPhaseDescendantBlockBackgrounds;
     }
 
-    unsigned m_layerType : 2; // PaintLayerType
-
     // Self-painting layer is an optimization where we avoid the heavy Layer painting
     // machinery for a Layer allocated only to handle the overflow clip case.
     // FIXME(crbug.com/332791): Self-painting layer should be merged into the overflow-only concept.