Remove dead code in CSSValuePool.

Source/core/css/CSSValuePool.h

Index: Source/core/css/CSSValuePool.h
diff --git a/Source/core/css/CSSValuePool.h b/Source/core/css/CSSValuePool.h
index 2d4d7d1fd5a2dc619400957f7bbdee4db43a7fa4..5b90ee769d986bb0dafc17b9e9ef2c8f59a7b1df 100644
--- a/Source/core/css/CSSValuePool.h
+++ b/Source/core/css/CSSValuePool.h
@@ -52,8 +52,6 @@ public:
     PassRefPtr<CSSPrimitiveValue> createValue(const String& value, CSSPrimitiveValue::UnitTypes type) { return CSSPrimitiveValue::create(value, type); }
     template<typename T> static PassRefPtr<CSSPrimitiveValue> createValue(T value) { return CSSPrimitiveValue::create(value); }
 
-    void drain();
-
 private:
     CSSValuePool();