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

Source/core/dom/StyleEngine.cpp

Index: Source/core/dom/StyleEngine.cpp
diff --git a/Source/core/dom/StyleEngine.cpp b/Source/core/dom/StyleEngine.cpp
index 25f033737f28e93a14dc0368016b6865301dddad..4dea159ad16c33d98c12817547a088c72de7959f 100644
--- a/Source/core/dom/StyleEngine.cpp
+++ b/Source/core/dom/StyleEngine.cpp
@@ -464,4 +464,19 @@ void StyleEngine::appendActiveAuthorStyleSheets(StyleResolver* styleResolver)
     styleResolver->setBuildScopedStyleTreeInDocumentOrder(false);
 }
 
+StyleSheetContents* StyleEngine::findStyleSheetContents(const AtomicString& sheetText)
+{
+    return m_styleSheetContentsCache.find(sheetText);
+}
+
+void StyleEngine::registerStyleSheetContents(const AtomicString& sheetText, StyleSheetContents* contents)
+{
+    m_styleSheetContentsCache.add(sheetText, contents);
+}
+
+void StyleEngine::unregisterStyleSheetContents(const AtomicString& sheetText)
+{
+    m_styleSheetContentsCache.remove(sheetText);
+}
+
 }