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 8d902cd52e21c44170e669d15f4a279d8e1a9cfc..7730ffdb12fae5b69845ec71ccacf726d45dc2fe 100644
--- a/Source/core/dom/StyleEngine.cpp
+++ b/Source/core/dom/StyleEngine.cpp
@@ -445,4 +445,41 @@ void StyleEngine::appendActiveAuthorStyleSheets(StyleResolver* styleResolver)
     styleResolver->setBuildScopedStyleTreeInDocumentOrder(false);
 }
 
+StyleSheetContents* StyleEngine::findStyleSheetContents(const AtomicString& sheetText)
+{
+    if (sheetText.isEmpty())
+        return 0;
+
+    HashMap<AtomicString, std::pair<unsigned, RefPtr<StyleSheetContents> > >::iterator it = m_styleSheetContentsCache.find(sheetText);
+    if (it == m_styleSheetContentsCache.end())
+        return 0;
+    return it->value.second.get();
+}
+
+void StyleEngine::registerStyleSheetContents(const AtomicString& sheetText, StyleSheetContents* contents)
+{
+    ASSERT(contents);
+    ASSERT(!sheetText.isEmpty());
+    HashMap<AtomicString, std::pair<unsigned, RefPtr<StyleSheetContents> > >::AddResult result = m_styleSheetContentsCache.add(sheetText, std::pair<unsigned, RefPtr<StyleSheetContents> >(0, 0));
+    if (!result.isNewEntry) {
+        result.iterator->value.first++;
+        return;
+    }
+    result.iterator->value.first = 1;
+    result.iterator->value.second = contents->copy();
+}
+
+void StyleEngine::unregisterStyleSheetContents(const AtomicString& sheetText)
+{
+    ASSERT(!sheetText.isEmpty());
+    HashMap<AtomicString, std::pair<unsigned, RefPtr<StyleSheetContents> >  >::iterator it = m_styleSheetContentsCache.find(sheetText);
+    if (it == m_styleSheetContentsCache.end())
+        return;
+    ASSERT(it->value.first > 0);
+    it->value.first--;
+    if (it->value.first)
+        return;
+    m_styleSheetContentsCache.remove(sheetText);
+}
+
 }