Slightly simplify building FillLayer objects

Source/core/rendering/style/FillLayer.h

Index: Source/core/rendering/style/FillLayer.h
diff --git a/Source/core/rendering/style/FillLayer.h b/Source/core/rendering/style/FillLayer.h
index 3362f5afaf8fc88e013fe29df9e2c810bb232a27..461fd6f4ec95ddfb38e7b1d19b206462553da659 100644
--- a/Source/core/rendering/style/FillLayer.h
+++ b/Source/core/rendering/style/FillLayer.h
@@ -84,6 +84,12 @@ public:
 
     const FillLayer* next() const { return m_next; }
     FillLayer* next() { return m_next; }
+    FillLayer* ensureNext()
+    {
+        if (!m_next)
+            m_next = new FillLayer(type());
+        return m_next;
+    }
 
     bool isImageSet() const { return m_imageSet; }
     bool isXPositionSet() const { return m_xPosSet; }
@@ -139,8 +145,6 @@ public:
     void clearSize() { m_sizeType = SizeNone; }
     void clearMaskSourceType() { m_maskSourceTypeSet = false; }
 
-    void setNext(FillLayer* n) { if (m_next != n) { delete m_next; m_next = n; } }
-
     FillLayer& operator=(const FillLayer& o);
     FillLayer(const FillLayer& o);