StyleResolver should update RuleSets lazily.

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index 00c2016fa9359e21c64a70928aa004df5967e4ef..6f8bfcf487a6385f606b878462b2476f91aa5e8d 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -635,6 +635,8 @@ MediaQueryMatcher& Document::mediaQueryMatcher()
 {
     if (!m_mediaQueryMatcher)
         m_mediaQueryMatcher = MediaQueryMatcher::create(this);
+    if (m_styleResolver && m_styleResolver->hasPendingAuthorStyleSheets())
+        m_styleResolver->appendPendingAuthorStyleSheets();
     return *m_mediaQueryMatcher;
 }
 
@@ -1700,6 +1702,9 @@ void Document::recalcStyle(StyleRecalcChange change)
     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;
@@ -1887,12 +1892,18 @@ PassRefPtr<RenderStyle> Document::styleForElementIgnoringPendingStylesheets(Elem
 {
     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)
@@ -1958,6 +1969,14 @@ void Document::createStyleResolver()
     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();