Remove CSSStyleDeclaration::copyProperties()

Source/core/css/PropertySetCSSStyleDeclaration.cpp

Index: Source/core/css/PropertySetCSSStyleDeclaration.cpp
diff --git a/Source/core/css/PropertySetCSSStyleDeclaration.cpp b/Source/core/css/PropertySetCSSStyleDeclaration.cpp
index ec18cbeeedac2e5c18277bd4792c62e5b8d8e21a..7b7e1423bf0b1537aa3ec49ed1df5b9b450f4891 100644
--- a/Source/core/css/PropertySetCSSStyleDeclaration.cpp
+++ b/Source/core/css/PropertySetCSSStyleDeclaration.cpp
@@ -268,11 +268,6 @@ StyleSheetContents* AbstractPropertySetCSSStyleDeclaration::contextStyleSheet()
     return cssStyleSheet ? cssStyleSheet->contents() : 0;
 }
 
-PassRefPtrWillBeRawPtr<MutableStylePropertySet> AbstractPropertySetCSSStyleDeclaration::copyProperties() const
-{
-    return propertySet().mutableCopy();
-}
-
 bool AbstractPropertySetCSSStyleDeclaration::cssPropertyMatches(CSSPropertyID propertyID, const CSSValue* propertyValue) const
 {
     return propertySet().propertyMatches(propertyID, propertyValue);