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

Source/core/dom/StyleEngine.h

Index: Source/core/dom/StyleEngine.h
diff --git a/Source/core/dom/StyleEngine.h b/Source/core/dom/StyleEngine.h
index 2c70a5b0d150107b4e0c705204e39886ae2aa23c..7851ef946b3ff49dffeb05f2e4c95d85c2b590bc 100644
--- a/Source/core/dom/StyleEngine.h
+++ b/Source/core/dom/StyleEngine.h
@@ -35,6 +35,7 @@
 #include "wtf/ListHashSet.h"
 #include "wtf/RefPtr.h"
 #include "wtf/Vector.h"
+#include "wtf/text/AtomicString.h"
 #include "wtf/text/WTFString.h"
 
 namespace WebCore {
@@ -110,6 +111,11 @@ public:
     void appendActiveAuthorStyleSheets(StyleResolver*);
     void getActiveAuthorStyleSheets(Vector<const Vector<RefPtr<CSSStyleSheet> >*>& activeAuthorStyleSheets) const;
 
+    // CSSStyleContents cache.
+    StyleSheetContents* findStyleSheetContents(const AtomicString&);
+    void registerStyleSheetContents(const AtomicString&, StyleSheetContents*);
+    void unregisterStyleSheetContents(const AtomicString&);
+
 private:
     StyleEngine(Document&);
 
@@ -154,6 +160,9 @@ private:
     bool m_usesFirstLineRules;
     bool m_usesFirstLetterRules;
     bool m_usesRemUnits;
+
+    // Mapping from textContents of StyleElement to a pair of StyleSheetContent(second) and its usages(first).

[dglazkov, 2013/10/18 16:56:19]

Can we move this into a separate class, which is contained by StyleEngine.h?

[tasak, 2013/10/21 12:27:37]

Done.

+    HashMap<AtomicString, std::pair<unsigned, RefPtr<StyleSheetContents> > > m_styleSheetContentsCache;
 };
 
 }