Replace RenderArena with PartitionAlloc.

Source/core/rendering/RenderLayer.h

Index: Source/core/rendering/RenderLayer.h
diff --git a/Source/core/rendering/RenderLayer.h b/Source/core/rendering/RenderLayer.h
index 89c41e6fafa02086a63b0c0102594ad21414a711..77d6943172580cbd285ee69c0610425e14253c83 100644
--- a/Source/core/rendering/RenderLayer.h
+++ b/Source/core/rendering/RenderLayer.h
@@ -778,12 +778,9 @@ public:
 
     bool hasBlendMode() const;
 
-    // Overloaded new operator. Derived classes must override operator new
-    // in order to allocate out of the RenderArena.
-    void* operator new(size_t, RenderArena*);
-
-    // Overridden to prevent the normal delete from being called.
-    void operator delete(void*, size_t);
+#if ENABLE(PARTITION_ALLOC)
+    void* operator new(size_t);
+#endif
 
     bool isComposited() const { return m_backing != 0; }
     bool hasCompositedMask() const;
@@ -875,6 +872,10 @@ public:
     void setForceNeedsCompositedScrolling(ForceNeedsCompositedScrollingMode);
 
 private:
+#if ENABLE(PARTITION_ALLOC)
+    void operator delete(void*);
+#endif
+
     enum CollectLayersBehavior {
         ForceLayerToStackingContainer,
         OverflowScrollCanBeStackingContainers,
@@ -951,9 +952,6 @@ private:
 
     IntSize clampScrollOffset(const IntSize&) const;
 
-    // The normal operator new is disallowed on all render objects.
-    void* operator new(size_t) throw();
-
     void setNextSibling(RenderLayer* next) { m_next = next; }
     void setPreviousSibling(RenderLayer* prev) { m_previous = prev; }
     void setParent(RenderLayer* parent);
@@ -1148,8 +1146,8 @@ private:
     friend class RenderLayerCompositor;
     friend class RenderLayerModelObject;
 
-    // Only safe to call from RenderBoxModelObject::destroyLayer(RenderArena*)
-    void destroy(RenderArena*);
+    // Only safe to call from RenderBoxModelObject::destroyLayer()
+    void destroy();
 
     LayoutUnit overflowTop() const;
     LayoutUnit overflowBottom() const;