Move inline stylesheet cache decision making from StyleSheetContents to StyleEngine

Source/core/dom/StyleEngine.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 544 matching lines @@
     m_dirtyTreeScopes.add(&scope);
 }
 
 void StyleEngine::markDocumentDirty()
 {
     m_documentScopeDirty = true;
     if (!HTMLImport::isMaster(&m_document))
         m_document.import()->master()->styleEngine()->markDocumentDirty();
 }
 
+static bool isCacheableForStyleElement(const StyleSheetContents& contents)
+{
+    // FIXME: Support copying import rules.
+    if (!contents.importRules().isEmpty())
+        return false;
+    // Until import rules are supported in cached sheets it's not possible for loading to fail.
+    ASSERT(!contents.didLoadErrorOccur());
+    // It is not the original sheet anymore.
+    if (contents.isMutable())
+        return false;
+    if (!contents.hasSyntacticallyValidCSSHeader())
+        return false;
+    return true;
+}
+
 PassRefPtrWillBeRawPtr<CSSStyleSheet> StyleEngine::createSheet(Element* e, const String& text, TextPosition startPosition, bool createdByParser)
 {
     RefPtrWillBeRawPtr<CSSStyleSheet> styleSheet;
 
     e->document().styleEngine()->addPendingSheet();
 
     if (!e->document().inQuirksMode()) {
         AtomicString textContent(text);
 
         HashMap<AtomicString, StyleSheetContents*>::AddResult result = m_textToSheetCache.add(textContent, 0);
         if (result.isNewEntry || !result.storedValue->value) {
             styleSheet = StyleEngine::parseSheet(e, text, startPosition, createdByParser);
-            if (result.isNewEntry && styleSheet->contents()->maybeCacheable()) {
+            if (result.isNewEntry && isCacheableForStyleElement(*styleSheet->contents())) {
                 result.storedValue->value = styleSheet->contents();
                 m_sheetToTextCache.add(styleSheet->contents(), textContent);
             }
         } else {
-            ASSERT(result.storedValue->value->maybeCacheable());
-            ASSERT(result.storedValue->value->singleOwnerDocument() == e->document());
-            styleSheet = CSSStyleSheet::createInline(result.storedValue->value, e, startPosition);
+            StyleSheetContents* contents = result.storedValue->value;
+            ASSERT(contents);
+            ASSERT(isCacheableForStyleElement(*contents));
+            ASSERT(contents->singleOwnerDocument() == e->document());
+            styleSheet = CSSStyleSheet::createInline(contents, e, startPosition);
         }
     } else {
         // FIXME: currently we don't cache StyleSheetContents inQuirksMode.
         styleSheet = StyleEngine::parseSheet(e, text, startPosition, createdByParser);
     }
 
     ASSERT(styleSheet);
     styleSheet->setTitle(e->title());
     return styleSheet;
 }
@@ skipping 18 matching lines @@
 
 void StyleEngine::trace(Visitor* visitor)
 {
     visitor->trace(m_injectedAuthorStyleSheets);
     visitor->trace(m_authorStyleSheets);
     visitor->trace(m_documentStyleSheetCollection);
     visitor->trace(m_styleSheetCollectionMap);
 }
 
 }