Devirtualize several mediastream class destructors

Source/modules/mediastream/RTCSessionDescription.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 57 matching lines @@
 {
     return adoptRef(new RTCSessionDescription(webSessionDescription));
 }
 
 RTCSessionDescription::RTCSessionDescription(WebKit::WebRTCSessionDescription webSessionDescription)
     : m_webSessionDescription(webSessionDescription)
 {
     ScriptWrappable::init(this);
 }
 
-RTCSessionDescription::~RTCSessionDescription()
-{
-}
-
 String RTCSessionDescription::type()
 {
     return m_webSessionDescription.type();
 }
 
 void RTCSessionDescription::setType(const String& type, ExceptionState& es)
 {
     if (verifyType(type))
         m_webSessionDescription.setType(type);
     else
         es.throwDOMException(TypeMismatchError, constructIllegalTypeExceptionMessage(type));
 }
 
 String RTCSessionDescription::sdp()
 {
     return m_webSessionDescription.sdp();
 }
 
 void RTCSessionDescription::setSdp(const String& sdp)
 {
     m_webSessionDescription.setSDP(sdp);
 }
 
 WebKit::WebRTCSessionDescription RTCSessionDescription::webSessionDescription()
 {
     return m_webSessionDescription;
 }
 
 } // namespace WebCore