Switch URL and URLUtils interfaces over to use ScalarValueString.

LayoutTests/fast/domurl/url-hash.html

Index: LayoutTests/fast/domurl/url-hash.html
diff --git a/LayoutTests/fast/domurl/url-hash.html b/LayoutTests/fast/domurl/url-hash.html
index a13916aa3e43314494530090699865385849bdc3..0ec9d75990ff3b7da3e0c27a7762cb114a31a1af 100644
--- a/LayoutTests/fast/domurl/url-hash.html
+++ b/LayoutTests/fast/domurl/url-hash.html
@@ -48,4 +48,12 @@ test(function() {
     assert_equals(url.href, 'invalid');
 }, 'hash property invalid URL');
 
+test(function() {
+    var url = new URL('http://www.domain.com/');
+    assert_equals(url.hash, '');
+
+    url.hash = '\udc01\ud802a';
+    assert_equals(url.hash, '#\ufffd\ufffda');
+}, 'hash with unmatched surrogates');
+
 </script>