Serialize <string> with double quotes

Source/core/css/CSSPrimitiveValue.cpp

Index: Source/core/css/CSSPrimitiveValue.cpp
diff --git a/Source/core/css/CSSPrimitiveValue.cpp b/Source/core/css/CSSPrimitiveValue.cpp
index 60b83526c917d22055691e2bc2febfba2c2f4563..2f4e6e04417ecb97a90cb7fb09ef558e24f34190 100644
--- a/Source/core/css/CSSPrimitiveValue.cpp
+++ b/Source/core/css/CSSPrimitiveValue.cpp
@@ -1062,9 +1062,12 @@ String CSSPrimitiveValue::customCSSText() const
         case CSS_CUSTOM_IDENT:
             text = quoteCSSStringIfNeeded(m_value.string);
             break;
-        case CSS_STRING:
-            text = quoteCSSString(m_value.string);
+        case CSS_STRING: {
+            StringBuilder result;
+            serializeString(m_value.string, result);
+            text = result.toString();
             break;
+        }
         case CSS_URI:
             text = "url(" + quoteCSSURLIfNeeded(m_value.string) + ")";
             break;