Remove additionalOutlineSize in ShadowList: it is always 0.

Source/core/rendering/style/ShadowList.h

Index: Source/core/rendering/style/ShadowList.h
diff --git a/Source/core/rendering/style/ShadowList.h b/Source/core/rendering/style/ShadowList.h
index 7efea7d7da4907e18e3349c4578bfa167967dbbc..619c108547f3720cc5413a90001b30c4485a6a8b 100644
--- a/Source/core/rendering/style/ShadowList.h
+++ b/Source/core/rendering/style/ShadowList.h
@@ -60,8 +60,8 @@ public:
 
     static PassRefPtr<ShadowList> blend(const ShadowList* from, const ShadowList* to, double progress);
 
-    void adjustRectForShadow(LayoutRect&, float additionalOutlineSize = 0) const;
-    void adjustRectForShadow(FloatRect&, float additionalOutlineSize = 0) const;
+    void adjustRectForShadow(LayoutRect&) const;
+    void adjustRectForShadow(FloatRect&) const;
 
     PassOwnPtr<DrawLooperBuilder> createDrawLooper(DrawLooperBuilder::ShadowAlphaMode, bool isHorizontal = true) const;