Block the HTML parser on external stylesheets

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 2077 matching lines @@
 void Document::setIsViewSource(bool isViewSource)
 {
     m_isViewSource = isViewSource;
     if (!m_isViewSource)
         return;
 
     setSecurityOrigin(SecurityOrigin::createUnique());
     didUpdateSecurityOrigin();
 }
 
+bool Document::isRenderingReady() const 
+{
+    return haveImportsLoaded() && (RuntimeEnabledFeatures::htmlParserBlocksOnCSSEnabled() || haveStylesheetsLoaded());

[esprehn, 2016/03/07 21:35:50]

I don't think you want to do this, isRenderingReady() prevents painting, but the
parser being blocked on sheet shouldn't block painting. You want the content to
paint.

[Pat Meenan, 2016/03/07 21:49:53]

Right.  The change basically removes the check of stylesheets having been loaded
from the "isRenderingReady" check.  When the new code is enabled, the pending
stylesheets won't be checked for "isRenderingReady".

Given that I need to look at blocking on imports as well this will change a bit
though and neither will block rendering when the code is enabled.

+}
+
 bool Document::dirtyElementsForLayerUpdate()
 {
     if (m_layerUpdateSVGFilterElements.isEmpty())
         return false;
 
     for (Element* element : m_layerUpdateSVGFilterElements)
         element->setNeedsStyleRecalc(LocalStyleChange, StyleChangeReasonForTracing::create(StyleChangeReason::SVGFilterLayerUpdate));
     m_layerUpdateSVGFilterElements.clear();
     return true;
 }
@@ skipping 3882 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().getString().utf8().data());
 }
 #endif