Serialize <string> with double quotes

LayoutTests/fast/css/content-language-dynamically-added.html

Index: LayoutTests/fast/css/content-language-dynamically-added.html
diff --git a/LayoutTests/fast/css/content-language-dynamically-added.html b/LayoutTests/fast/css/content-language-dynamically-added.html
index f9f3e6a1785ad38ec45a315996f42c26aacde524..32616ba3012c7dda4a3ba88c1e25fe76fb600914 100644
--- a/LayoutTests/fast/css/content-language-dynamically-added.html
+++ b/LayoutTests/fast/css/content-language-dynamically-added.html
@@ -23,14 +23,14 @@ function languageOfNode(id) {
     return window.getComputedStyle(element).webkitLocale;
 }
 shouldBeEqualToString("languageOfNode('x')", "auto");
-shouldBeEqualToString("languageOfNode('y')", "'ar'");
+shouldBeEqualToString("languageOfNode('y')", '"ar"');
 
 var meta = document.createElement("meta");
 meta.httpEquiv = "content-language";
 meta.content = "ja";
 document.getElementById("head").appendChild(meta);
-shouldBeEqualToString("languageOfNode('x')", "'ja'");
-shouldBeEqualToString("languageOfNode('y')", "'ar'");
+shouldBeEqualToString("languageOfNode('x')", '"ja"');
+shouldBeEqualToString("languageOfNode('y')", '"ar"');
 </script>
 </body>
 </html>