Simplify WindowProxy handoff in WebFrame::swap().

Source/core/frame/Frame.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Simon Hausmann <hausmann@kde.org>
  *                     2000 Stefan Schimanski <1Stein@gmx.de>
  *                     2001 George Staikos <staikos@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2005 Alexey Proskuryakov <ap@nypop.com>
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
@@ skipping 140 matching lines @@
     return client;
 }
 
 ChromeClient& Frame::chromeClient() const
 {
     if (Page* page = this->page())
         return page->chromeClient();
     return emptyChromeClient();
 }
 
-void Frame::prepareSwapFrom(Frame* old)
-{
-    WindowProxyManager* oldManager = old->windowProxyManager();
-    oldManager->clearForNavigation();
-}
-
 void Frame::finishSwapFrom(Frame* old)
 {
     WindowProxyManager* oldManager = old->windowProxyManager();
+    oldManager->clearForNavigation();
     windowProxyManager()->takeGlobalFrom(oldManager);
 }
 
 Frame* Frame::findFrameForNavigation(const AtomicString& name, Frame& activeFrame)
 {
     Frame* frame = tree().find(name);
     if (!frame || !activeFrame.canNavigate(*frame))
         return nullptr;
     return frame;
 }
@@ skipping 127 matching lines @@
 
     if (m_owner) {
         if (m_owner->isLocal())
             toHTMLFrameOwnerElement(m_owner)->setContentFrame(*this);
     } else {
         page()->setMainFrame(this);
     }
 }
 
 } // namespace blink