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

Source/core/css/StyleSheetContents.h

Index: Source/core/css/StyleSheetContents.h
diff --git a/Source/core/css/StyleSheetContents.h b/Source/core/css/StyleSheetContents.h
index 0a7bde9ef230f833a01536ed15dff83ce21e8926..415b41749d5e84cea053f480fabc9f0465b02182 100644
--- a/Source/core/css/StyleSheetContents.h
+++ b/Source/core/css/StyleSheetContents.h
@@ -70,6 +70,7 @@ public:
     bool parseStringAtPosition(const String&, const TextPosition&, bool);
 
     bool isCacheable() const;
+    bool maybeCacheable() const;
 
     bool isLoading() const;
 
@@ -83,12 +84,12 @@ public:
 
     const String& charset() const { return m_parserContext.charset(); }
 
-    bool loadCompleted() const { return m_loadCompleted; }
+    bool loadCompleted() const;
     bool hasFailedOrCanceledSubresources() const;
 
     KURL completeURL(const String& url) const;
 
-    void setHasSyntacticallyValidCSSHeader(bool b) { m_hasSyntacticallyValidCSSHeader = b; }
+    void setHasSyntacticallyValidCSSHeader(bool isValidCss);
     bool hasSyntacticallyValidCSSHeader() const { return m_hasSyntacticallyValidCSSHeader; }
 
     void setHasFontFaceRule(bool b) { m_hasFontFaceRule = b; }
@@ -157,6 +158,7 @@ private:
     void notifyRemoveFontFaceRule(const StyleRuleFontFace*);
 
     void clearCharsetRule();
+    void clearCache();
 
     StyleRuleImport* m_ownerRule;
 
@@ -168,7 +170,6 @@ private:
     typedef HashMap<AtomicString, AtomicString> PrefixNamespaceURIMap;
     PrefixNamespaceURIMap m_namespaces;
 
-    bool m_loadCompleted : 1;
     bool m_hasSyntacticallyValidCSSHeader : 1;
     bool m_didLoadErrorOccur : 1;
     bool m_usesRemUnits : 1;