Use reference for FillLayer if possible

Source/core/rendering/style/RenderStyle.cpp

Index: Source/core/rendering/style/RenderStyle.cpp
diff --git a/Source/core/rendering/style/RenderStyle.cpp b/Source/core/rendering/style/RenderStyle.cpp
index 624ec2af859cc90866a489c67ae2651e63a91db1..1da5456a9b73bbdaf80f3d5d4a7a4469ffa26ce3 100644
--- a/Source/core/rendering/style/RenderStyle.cpp
+++ b/Source/core/rendering/style/RenderStyle.cpp
@@ -1012,14 +1012,14 @@ RoundedRect RenderStyle::getRoundedInnerBorderFor(const LayoutRect& borderRect,
     return roundedRect;
 }
 
-static bool allLayersAreFixed(const FillLayer* layer)
+static bool allLayersAreFixed(const FillLayer& layer)
 {
-    bool allFixed = true;
-
-    for (const FillLayer* currLayer = layer; currLayer; currLayer = currLayer->next())
-        allFixed &= (currLayer->image() && currLayer->attachment() == FixedBackgroundAttachment);
+    for (const FillLayer* currLayer = &layer; currLayer; currLayer = currLayer->next()) {
+        if (!currLayer->image() || currLayer->attachment() != FixedBackgroundAttachment)
+            return false;
+    }
 
-    return layer && allFixed;
+    return true;
 }
 
 bool RenderStyle::hasEntirelyFixedBackground() const