Removed the non-const version of PropertyReference::value()

third_party/WebKit/Source/core/frame/FrameSerializer.cpp

Index: third_party/WebKit/Source/core/frame/FrameSerializer.cpp
diff --git a/third_party/WebKit/Source/core/frame/FrameSerializer.cpp b/third_party/WebKit/Source/core/frame/FrameSerializer.cpp
index 1eb5ceca79680d5903d60d3544a8599691aabb28..5084c241fe5710a0a2637f07fe14d98128d0db04 100644
--- a/third_party/WebKit/Source/core/frame/FrameSerializer.cpp
+++ b/third_party/WebKit/Source/core/frame/FrameSerializer.cpp
@@ -430,7 +430,7 @@ void FrameSerializer::retrieveResourcesForProperties(const StylePropertySet* sty
     // image properties there might be.
     unsigned propertyCount = styleDeclaration->propertyCount();
     for (unsigned i = 0; i < propertyCount; ++i) {
-        CSSValue* cssValue = styleDeclaration->propertyAt(i).value();
+        const CSSValue* cssValue = styleDeclaration->propertyAt(i).value();
         retrieveResourcesForCSSValue(*cssValue, document);
     }
 }