Avoid reparsing keyframe selectors

Source/core/css/WebKitCSSKeyframeRule.h

Index: Source/core/css/WebKitCSSKeyframeRule.h
diff --git a/Source/core/css/WebKitCSSKeyframeRule.h b/Source/core/css/WebKitCSSKeyframeRule.h
index e4c4094740513d4a06949639d6773ce8d2f806f5..9d3337cc5e09150ec810977b1439a2799f3a2914 100644
--- a/Source/core/css/WebKitCSSKeyframeRule.h
+++ b/Source/core/css/WebKitCSSKeyframeRule.h
@@ -44,10 +44,12 @@ public:
     }
     ~StyleKeyframe();
 
-    String keyText() const { return m_key; }
-    void setKeyText(const String& s) { m_key = s; }
+    String keyText() const;
+    void setKeyText(const String&);
+    void setKeys(const Vector<float>&);
+    bool isValid() const { return m_keys.size() > 0 || !m_keyText.isEmpty(); }
 
-    void getKeys(Vector<float>& keys) const   { parseKeyString(m_key, keys); }
+    Vector<float> getKeys() const { return m_keys; }
     
     const StylePropertySet* properties() const { return m_properties.get(); }
     StylePropertySet* mutableProperties();
@@ -60,12 +62,11 @@ public:
 private:
     StyleKeyframe();
     
-    static void parseKeyString(const String&, Vector<float>& keys);
+    static Vector<float> parseKeyString(const String&);
     
     RefPtr<StylePropertySet> m_properties;
-    // FIXME: This should be a parsed vector of floats.
-    // comma separated list of keys
-    String m_key;
+    mutable String m_keyText;
+    Vector<float> m_keys;
 };
 
 class WebKitCSSKeyframeRule : public CSSRule {