Refactor frame navigation/detach state cleanup to be more sane.

Source/core/frame/LocalDOMWindow.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  *
  * 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 293 matching lines @@
 #if ENABLE(OILPAN)
     ThreadState::current()->registerPreFinalizer(*this);
 #endif
 }
 
 void LocalDOMWindow::clearDocument()
 {
     if (!m_document)
         return;
 
-    if (m_document->isActive()) {
-        // FIXME: We don't call willRemove here. Why is that OK?
-        // This detach() call is also mostly redundant. Most of the calls to
-        // this function come via DocumentLoader::createWriterFor, which
-        // always detaches the previous Document first. Only XSLTProcessor
-        // depends on this detach() call, so it seems like there's some room
-        // for cleanup.
-        m_document->detach();
-    }
+    ASSERT(!m_document->isActive());
 
     // FIXME: This should be part of ActiveDOMObject shutdown
     clearEventQueue();
 
     m_document->clearDOMWindow();
     m_document = nullptr;
 }
 
 void LocalDOMWindow::clearEventQueue()
 {
@@ skipping 1326 matching lines @@
     return m_frameObserver->frame();
 }
 
 v8::Handle<v8::Object> LocalDOMWindow::wrap(v8::Handle<v8::Object> creationContext, v8::Isolate* isolate)
 {
     ASSERT_NOT_REACHED(); // LocalDOMWindow has [Custom=ToV8].
     return v8::Handle<v8::Object>();
 }
 
 } // namespace blink