StyleResolver should update RuleSets lazily.

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 617 matching lines @@
 {
     if (!m_selectorQueryCache)
         m_selectorQueryCache = adoptPtr(new SelectorQueryCache());
     return *m_selectorQueryCache;
 }
 
 MediaQueryMatcher& Document::mediaQueryMatcher()
 {
     if (!m_mediaQueryMatcher)
         m_mediaQueryMatcher = MediaQueryMatcher::create(this);
+    if (m_styleResolver && m_styleResolver->hasPendingAuthorStyleSheets())
+        m_styleResolver->appendPendingAuthorStyleSheets();
     return *m_mediaQueryMatcher;
 }
 
 void Document::setCompatibilityMode(CompatibilityMode mode)
 {
     if (m_compatibilityModeLocked || mode == m_compatibilityMode)
         return;
     bool wasInQuirksMode = inQuirksMode();
     m_compatibilityMode = mode;
     selectorQueryCache().invalidate();
@@ skipping 1045 matching lines @@
     // resolves style (here) and then when we resolve style on the parent chain, we may end up
     // re-attaching our containing iframe, which when asked HTMLFrameElementBase::isURLAllowed
     // hits a null-dereference due to security code always assuming the document has a SecurityOrigin.
 
     if (m_styleEngine->needsUpdateActiveStylesheetsOnStyleRecalc())
         m_styleEngine->updateActiveStyleSheets(FullStyleUpdate);
 
     if (m_elemSheet && m_elemSheet->contents()->usesRemUnits())
         m_styleEngine->setUsesRemUnit(true);
 
+    if (m_styleResolver && m_styleResolver->hasPendingAuthorStyleSheets())
+        m_styleResolver->appendPendingAuthorStyleSheets();

[esprehn, 2013/10/25 02:37:58]

You shouldn't be repeated this everywhere. Just like with style and layout there
should be an updateSheetsIfNeeded() like call that's inline and returns early if
no update is needed.

[tasak, 2013/10/25 10:10:10]

I see.
I added an inline function to StyleResolver.h, and modified to sue the function.

+
     {
         PostAttachCallbacks::SuspendScope suspendPostAttachCallbacks;
         RenderWidget::UpdateSuspendScope suspendWidgetHierarchyUpdates;
         FrameView::DeferredRepaintScope deferRepaints(*view());
         TemporaryChange<bool> changeInStyleRecalc(m_inStyleRecalc, true);
 
         if (styleChangeType() >= SubtreeStyleChange)
             change = Force;
 
         if (change == Force || (change >= Inherit && shouldDisplaySeamlesslyWithParent())) {
@@ skipping 167 matching lines @@
     updateLayout();
 
     if (view())
         view()->partialLayout().reset();
 }
 
 PassRefPtr<RenderStyle> Document::styleForElementIgnoringPendingStylesheets(Element* element)
 {
     ASSERT_ARG(element, element->document() == this);
     TemporaryChange<bool> ignoreStyleSheets(m_ignorePendingStylesheets, true);
-    return styleResolver()->styleForElement(element, element->parentNode() ? element->parentNode()->computedStyle() : 0);
+    StyleResolver* resolver = styleResolver();
+    if (resolver->hasPendingAuthorStyleSheets())
+        resolver->appendPendingAuthorStyleSheets();

[esprehn, 2013/10/25 02:37:58]

This doesn't make sense. You call appendPendingAuthorStyleSheets() inside
::styleResolver(), why do you again check it here?

[tasak, 2013/10/25 10:10:10]

Yeah, this is my mistake.
Since I removed the call from styleResolver(), I used the inline function in
StyleResolver.h here.

+    return resolver->styleForElement(element, element->parentNode() ? element->parentNode()->computedStyle() : 0);
 }
 
 PassRefPtr<RenderStyle> Document::styleForPage(int pageIndex)
 {
-    return styleResolver()->styleForPage(pageIndex);
+    StyleResolver* resolver = styleResolver();
+    if (resolver->hasPendingAuthorStyleSheets())
+        resolver->appendPendingAuthorStyleSheets();

[esprehn, 2013/10/25 02:37:58]

Same.

[tasak, 2013/10/25 10:10:10]

Done.

+    return resolver->styleForPage(pageIndex);
 }
 
 bool Document::isPageBoxVisible(int pageIndex)
 {
     return styleForPage(pageIndex)->visibility() != HIDDEN; // display property doesn't apply to @page.
 }
 
 void Document::pageSizeAndMarginsInPixels(int pageIndex, IntSize& pageSize, int& marginTop, int& marginRight, int& marginBottom, int& marginLeft)
 {
     RefPtr<RenderStyle> style = styleForPage(pageIndex);
@@ skipping 45 matching lines @@
 
 void Document::createStyleResolver()
 {
     bool matchAuthorAndUserStyles = true;
     if (Settings* docSettings = settings())
         matchAuthorAndUserStyles = docSettings->authorAndUserStylesEnabled();
     m_styleResolver = adoptPtr(new StyleResolver(*this, matchAuthorAndUserStyles));
     m_styleEngine->combineCSSFeatureFlags(m_styleResolver->ruleFeatureSet());
 }
 
+void Document::appendPendingAuthorStyleSheets()
+{
+    ASSERT(m_styleResolver);
+    if (!m_styleResolver->hasPendingAuthorStyleSheets())
+        return;
+    m_styleResolver->appendPendingAuthorStyleSheets();
+}
+
 void Document::clearStyleResolver()
 {
     m_styleResolver.clear();
 }
 
 void Document::attach(const AttachContext& context)
 {
     ASSERT(!confusingAndOftenMisusedAttached());
     ASSERT(!m_axObjectCache || this != topDocument());
 
@@ skipping 3383 matching lines @@
 void Document::modifiedStyleSheet(StyleSheet* sheet, RecalcStyleTime when, StyleResolverUpdateMode updateMode)
 {
     if (!isActive())
         return;
 
     styleEngine()->modifiedStyleSheet(sheet);
     styleResolverChanged(when, updateMode);
 }
 
 } // namespace WebCore