Add deprecation warnings for CSSValue accessors.

Source/core/frame/UseCounter.cpp

Index: Source/core/frame/UseCounter.cpp
diff --git a/Source/core/frame/UseCounter.cpp b/Source/core/frame/UseCounter.cpp
index 359503cf6ec57949a86aba2c6a12689b75c9f44c..d4266e4150a412fb8adc3e6cc47e012d52a76c92 100644
--- a/Source/core/frame/UseCounter.cpp
+++ b/Source/core/frame/UseCounter.cpp
@@ -685,6 +685,9 @@ String UseCounter::deprecationMessage(Feature feature)
     case AttributeSpecified:
         return "Attr.specified is deprecated. Its value is always true.";
 
+    case SVGElementGetPresentationAttribute:
+        return "CSSValue and SVGElement.getPresentationAttribute are deprecated. Please use getPropertyValue and parse the return value instead.";
+
     // Features that aren't deprecated don't have a deprecation message.
     default:
         return String();