IDL: Remove support for [LogPreviousValue] extended attribute

Source/web/WebDOMActivityLogger.cpp

Index: Source/web/WebDOMActivityLogger.cpp
diff --git a/Source/web/WebDOMActivityLogger.cpp b/Source/web/WebDOMActivityLogger.cpp
index 84e131efa07ed9600be2362f21a5dc354dd2067d..01f3d5684cd6bb6a63563fded57fb04ab6e010d2 100644
--- a/Source/web/WebDOMActivityLogger.cpp
+++ b/Source/web/WebDOMActivityLogger.cpp
@@ -57,11 +57,6 @@ public:
         m_domActivityLogger->logSetter(WebString(apiName), newValue, getURL(), getTitle());
     }
 
-    virtual void logSetter(const String& apiName, const v8::Handle<v8::Value>& newValue, const v8::Handle<v8::Value>& oldValue) OVERRIDE
-    {
-        m_domActivityLogger->logSetter(WebString(apiName), newValue, oldValue, getURL(), getTitle());
-    }
-
     virtual void logMethod(const String& apiName, int argc, const v8::Handle<v8::Value>* argv) OVERRIDE
     {
         m_domActivityLogger->logMethod(WebString(apiName), argc, argv, getURL(), getTitle());