CSSParser should return ImmutableStylePropertySets.

Source/core/css/CSSParser.cpp

Index: Source/core/css/CSSParser.cpp
diff --git a/Source/core/css/CSSParser.cpp b/Source/core/css/CSSParser.cpp
index 1d0e02b697fe9d15043465fc5064d9d140b8e6ce..6789b2c9af16930e97e3b9a0546d7e600d43ab38 100644
--- a/Source/core/css/CSSParser.cpp
+++ b/Source/core/css/CSSParser.cpp
@@ -1298,7 +1298,7 @@ void CSSParser::parseSelector(const String& string, CSSSelectorList& selectorLis
     m_selectorListForParseSelector = 0;
 }
 
-PassRefPtr<StylePropertySet> CSSParser::parseInlineStyleDeclaration(const String& string, Element* element)
+PassRefPtr<ImmutableStylePropertySet> CSSParser::parseInlineStyleDeclaration(const String& string, Element* element)
 {
     Document* document = element->document();
     CSSParserContext context = document->elementSheet()->contents()->parserContext();
@@ -1306,7 +1306,7 @@ PassRefPtr<StylePropertySet> CSSParser::parseInlineStyleDeclaration(const String
     return CSSParser(context, UseCounter::getFrom(document)).parseDeclaration(string, document->elementSheet()->contents());
 }
 
-PassRefPtr<StylePropertySet> CSSParser::parseDeclaration(const String& string, StyleSheetContents* contextStyleSheet)
+PassRefPtr<ImmutableStylePropertySet> CSSParser::parseDeclaration(const String& string, StyleSheetContents* contextStyleSheet)
 {
     setStyleSheet(contextStyleSheet);
 
@@ -1317,7 +1317,7 @@ PassRefPtr<StylePropertySet> CSSParser::parseDeclaration(const String& string, S
     if (m_hasFontFaceOnlyValues)
         deleteFontFaceOnlyValues();
 
-    RefPtr<StylePropertySet> style = createStylePropertySet();
+    RefPtr<ImmutableStylePropertySet> style = createStylePropertySet();
     clearProperties();
     return style.release();
 }
@@ -1392,7 +1392,7 @@ static inline void filterProperties(bool important, const CSSParser::ParsedPrope
     }
 }
 
-PassRefPtr<StylePropertySet> CSSParser::createStylePropertySet()
+PassRefPtr<ImmutableStylePropertySet> CSSParser::createStylePropertySet()
 {
     BitArray<numCSSProperties> seenProperties;
     size_t unusedEntries = m_parsedProperties.size();