Don't bother layout until first navigation is done.

third_party/WebKit/Source/core/dom/Document.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
@@ skipping 5420 matching lines @@
 bool Document::threadedParsingEnabledForTesting()
 {
     return s_threadedParsingEnabledForTesting;
 }
 
 bool Document::hasActiveParser()
 {
     return m_activeParserCount || (m_parser && m_parser->processingData());
 }
 
+bool Document::isInitialEmptyDocument() const
+{
+    return m_frame && !m_frame->loader().stateMachine()->committedFirstRealDocumentLoad();
+}
+
 void Document::setContextFeatures(ContextFeatures& features)
 {
     m_contextFeatures = PassRefPtrWillBeRawPtr<ContextFeatures>(features);
 }
 
 static LayoutObject* nearestCommonHoverAncestor(LayoutObject* obj1, LayoutObject* obj2)
 {
     if (!obj1 || !obj2)
         return 0;
 
@@ skipping 465 matching lines @@
 #ifndef NDEBUG
 using namespace blink;
 void showLiveDocumentInstances()
 {
     Document::WeakDocumentSet& set = Document::liveDocumentSet();
     fprintf(stderr, "There are %u documents currently alive:\n", set.size());
     for (Document* document : set)
         fprintf(stderr, "- Document %p URL: %s\n", document, document->url().string().utf8().data());
 }
 #endif