Avoid parsing css text if there are identical inline style blocks.

Source/core/css/StyleSheetContents.cpp

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2006, 2007, 2012 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 41 matching lines @@
     for (unsigned i = 0; i < m_importRules.size(); ++i) {
         if (StyleSheetContents* sheet = m_importRules[i]->styleSheet())
             size += sheet->estimatedSizeInBytes();
     }
     return size;
 }
 
 StyleSheetContents::StyleSheetContents(StyleRuleImport* ownerRule, const String& originalURL, const CSSParserContext& context)
     : m_ownerRule(ownerRule)
     , m_originalURL(originalURL)
-    , m_loadCompleted(false)
     , m_hasSyntacticallyValidCSSHeader(true)
     , m_didLoadErrorOccur(false)
     , m_usesRemUnits(false)
     , m_isMutable(false)
     , m_isInMemoryCache(false)
     , m_hasFontFaceRule(false)
     , m_hasMediaQueries(false)
     , m_parserContext(context)
 {
 }
 
 StyleSheetContents::StyleSheetContents(const StyleSheetContents& o)
     : RefCounted<StyleSheetContents>()
     , m_ownerRule(0)
     , m_originalURL(o.m_originalURL)
     , m_encodingFromCharsetRule(o.m_encodingFromCharsetRule)
     , m_importRules(o.m_importRules.size())
     , m_childRules(o.m_childRules.size())
     , m_namespaces(o.m_namespaces)
-    , m_loadCompleted(true)
     , m_hasSyntacticallyValidCSSHeader(o.m_hasSyntacticallyValidCSSHeader)
     , m_didLoadErrorOccur(false)
     , m_usesRemUnits(o.m_usesRemUnits)
     , m_isMutable(false)
     , m_isInMemoryCache(false)
     , m_hasFontFaceRule(o.m_hasFontFaceRule)
     , m_hasMediaQueries(o.m_hasMediaQueries)
     , m_parserContext(o.m_parserContext)
 {
     ASSERT(o.isCacheable());
 
     // FIXME: Copy import rules.
     ASSERT(o.m_importRules.isEmpty());
 
     for (unsigned i = 0; i < m_childRules.size(); ++i)
         m_childRules[i] = o.m_childRules[i]->copy();
 }
 
 StyleSheetContents::~StyleSheetContents()
 {
+    StyleEngine::removeSheet(this);
     clearRules();
 }
 
-bool StyleSheetContents::isCacheable() const
+void StyleSheetContents::setHasSyntacticallyValidCSSHeader(bool isValidCss)
+{
+    if (maybeCacheable() && !isValidCss)
+        StyleEngine::removeSheet(this);
+    m_hasSyntacticallyValidCSSHeader = isValidCss;
+}
+
+bool StyleSheetContents::maybeCacheable() const
 {
     // FIXME: StyleSheets with media queries can't be cached because their RuleSet
     // is processed differently based off the media queries, which might resolve
     // differently depending on the context of the parent CSSStyleSheet (e.g.
     // if they are in differently sized iframes). Once RuleSets are media query
     // agnostic, we can restore sharing of StyleSheetContents with medea queries.
     if (m_hasMediaQueries)
         return false;
     // FIXME: Support copying import rules.
     if (!m_importRules.isEmpty())
         return false;
     // FIXME: Support cached stylesheets in import rules.
     if (m_ownerRule)
         return false;
-    // This would require dealing with multiple clients for load callbacks.
-    if (!m_loadCompleted)
-        return false;
     if (m_didLoadErrorOccur)
         return false;
     // It is not the original sheet anymore.
     if (m_isMutable)
         return false;
     // If the header is valid we are not going to need to check the SecurityOrigin.
     // FIXME: Valid mime type avoids the check too.
     if (!m_hasSyntacticallyValidCSSHeader)
         return false;
     return true;
 }
 
+bool StyleSheetContents::isCacheable() const
+{
+    // This would require dealing with multiple clients for load callbacks.
+    if (!loadCompleted())
+        return false;
+    return maybeCacheable();
+}
+
 void StyleSheetContents::parserAppendRule(PassRefPtr<StyleRuleBase> rule)
 {
     ASSERT(!rule->isCharsetRule());
     if (rule->isImportRule()) {
         // Parser enforces that @import rules come before anything else except @charset.
         ASSERT(m_childRules.isEmpty());
         StyleRuleImport* importRule = toStyleRuleImport(rule.get());
         if (importRule->mediaQueries())
             setHasMediaQueries();
         m_importRules.append(importRule);
@@ skipping 194 matching lines @@
 
 bool StyleSheetContents::isLoading() const
 {
     for (unsigned i = 0; i < m_importRules.size(); ++i) {
         if (m_importRules[i]->isLoading())
             return true;
     }
     return false;
 }
 
+bool StyleSheetContents::loadCompleted() const
+{
+    StyleSheetContents* parentSheet = parentStyleSheet();
+    if (parentSheet)
+        return parentSheet->loadCompleted();

[esprehn, 2014/01/14 05:09:43]

So only the root ever has clients?

[tasak, 2014/01/14 08:03:54]

Yes, I think so.
Because singleOwnerNode() always checks rootStyleSheet()'s clients.

+
+    StyleSheetContents* root = rootStyleSheet();
+    for (unsigned i = 0; i < root->m_clients.size(); ++i) {
+        if (!root->m_clients[i]->loadCompleted())
+            return false;
+    }
+    return true;
+}
+
 void StyleSheetContents::checkLoaded()
 {
     if (isLoading())
         return;
 
     // Avoid |this| being deleted by scripts that run via
     // ScriptableDocumentParser::executeScriptsWaitingForResources().
     // See https://bugs.webkit.org/show_bug.cgi?id=95106
     RefPtr<StyleSheetContents> protect(this);
 
     StyleSheetContents* parentSheet = parentStyleSheet();
     if (parentSheet) {
         parentSheet->checkLoaded();
-        m_loadCompleted = true;
         return;
     }
-    RefPtr<Node> ownerNode = singleOwnerNode();
-    if (!ownerNode) {
-        m_loadCompleted = true;
+
+    StyleSheetContents* root = rootStyleSheet();
+    if (root->m_clients.isEmpty())
         return;
+
+    Vector<CSSStyleSheet*> clients(root->m_clients);
+    for (unsigned i = 0; i < clients.size(); ++i) {
+        // Avoid |CSSSStyleSheet| and |ownerNode| being deleted by scripts that run via
+        // ScriptableDocumentParser::executeScriptsWaitingForResources().
+        RefPtr<CSSStyleSheet> protectClient(clients[i]);
+
+        if (clients[i]->loadCompleted())
+            continue;
+
+        RefPtr<Node> ownerNode = clients[i]->ownerNode();
+        if (clients[i]->sheetLoaded())
+            ownerNode->notifyLoadedSheetAndAllCriticalSubresources(m_didLoadErrorOccur);
     }
-    m_loadCompleted = ownerNode->sheetLoaded();
-    if (m_loadCompleted)
-        ownerNode->notifyLoadedSheetAndAllCriticalSubresources(m_didLoadErrorOccur);
 }
 
 void StyleSheetContents::notifyLoadedSheet(const CSSStyleSheetResource* sheet)
 {
     ASSERT(sheet);
     m_didLoadErrorOccur |= sheet->errorOccurred();
     // updateLayoutIgnorePendingStyleSheets can cause us to create the RuleSet on this
     // sheet before its imports have loaded. So clear the RuleSet when the imports
     // load since the import's subrules are flattened into its parent sheet's RuleSet.
     clearRuleSet();
 }
 
 void StyleSheetContents::startLoadingDynamicSheet()
 {
-    if (Node* owner = singleOwnerNode())
-        owner->startLoadingDynamicSheet();
+    StyleSheetContents* root = rootStyleSheet();
+    for (unsigned i = 0; i < root->m_clients.size(); ++i)
+        root->m_clients[i]->startLoadingDynamicSheet();
 }
 
 StyleSheetContents* StyleSheetContents::rootStyleSheet() const
 {
     const StyleSheetContents* root = this;
     while (root->parentStyleSheet())
         root = root->parentStyleSheet();
     return const_cast<StyleSheetContents*>(root);
 }
 
@@ skipping 131 matching lines @@
     // See the StyleResolver calls in ScopedStyleResolver::addRulesFromSheet.
     for (size_t i = 0; i < m_clients.size(); ++i) {
         if (Document* document = m_clients[i]->ownerDocument())
             document->styleEngine()->clearResolver();
     }
     m_ruleSet.clear();
 }
 
 
 }