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 f7dc5c041d91a896b180cbc31c47a3c389e76f2e..6b121e34a32c67f3b954f11cc21a2b440edff51c 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -615,6 +615,7 @@ MediaQueryMatcher& Document::mediaQueryMatcher()
 {
     if (!m_mediaQueryMatcher)
         m_mediaQueryMatcher = MediaQueryMatcher::create(this);
+    appendPendingStyleSheetsIfNeeded(m_styleResolver.get());
     return *m_mediaQueryMatcher;
 }
 
@@ -1683,6 +1684,8 @@ void Document::recalcStyle(StyleRecalcChange change)
     if (m_elemSheet && m_elemSheet->contents()->usesRemUnits())
         m_styleEngine->setUsesRemUnit(true);
 
+    appendPendingStyleSheetsIfNeeded(m_styleResolver.get());
+
     {
         PostAttachCallbacks::SuspendScope suspendPostAttachCallbacks;
         RenderWidget::UpdateSuspendScope suspendWidgetHierarchyUpdates;
@@ -1870,12 +1873,16 @@ 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();
+    appendPendingStyleSheetsIfNeeded(resolver);
+    return resolver->styleForElement(element, element->parentNode() ? element->parentNode()->computedStyle() : 0);
 }
 
 PassRefPtr<RenderStyle> Document::styleForPage(int pageIndex)
 {
-    return styleResolver()->styleForPage(pageIndex);
+    StyleResolver* resolver = styleResolver();
+    appendPendingStyleSheetsIfNeeded(resolver);
+    return resolver->styleForPage(pageIndex);
 }
 
 bool Document::isPageBoxVisible(int pageIndex)