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 b7bfd7812150847bf216c8eb70bb73de667f6ba6..a646e8c47637f6c78c8c7f6b7b517b7c836def94 100644
--- a/Source/core/dom/StyleEngine.h
+++ b/Source/core/dom/StyleEngine.h
@@ -28,6 +28,7 @@
 #ifndef StyleEngine_h
 #define StyleEngine_h
 
+#include "core/css/StyleSheetContentsCache.h"
 #include "core/dom/Document.h"
 #include "core/dom/DocumentOrderedList.h"
 #include "core/dom/DocumentStyleSheetCollection.h"
@@ -35,6 +36,7 @@
 #include "wtf/ListHashSet.h"
 #include "wtf/RefPtr.h"
 #include "wtf/Vector.h"
+#include "wtf/text/AtomicString.h"
 #include "wtf/text/WTFString.h"
 
 namespace WebCore {
@@ -111,6 +113,8 @@ public:
     void appendActiveAuthorStyleSheets(StyleResolver*);
     void getActiveAuthorStyleSheets(Vector<const Vector<RefPtr<CSSStyleSheet> >*>& activeAuthorStyleSheets) const;
 
+    StyleSheetContentsCache& styleSheetContentsCache() { return m_styleSheetContentsCache; }
+
 private:
     StyleEngine(Document&);
 
@@ -155,6 +159,8 @@ private:
     bool m_usesFirstLineRules;
     bool m_usesFirstLetterRules;
     bool m_usesRemUnits;
+
+    StyleSheetContentsCache m_styleSheetContentsCache;
 };
 
 }