DOMException toString is not correct

LayoutTests/fast/dom/document-set-body.html

Index: LayoutTests/fast/dom/document-set-body.html
diff --git a/LayoutTests/fast/dom/document-set-body.html b/LayoutTests/fast/dom/document-set-body.html
index e7008bbb8f678caf364454023bc492ce85280329..a042456d2720aa7bdd22246a2de7e9792872f0fe 100644
--- a/LayoutTests/fast/dom/document-set-body.html
+++ b/LayoutTests/fast/dom/document-set-body.html
@@ -11,10 +11,10 @@ iframe1 = document.createElement('iframe');
 document.body.appendChild(iframe1);
 document1 = iframe1.contentDocument.implementation.createHTMLDocument("document");
 
-shouldThrow("document1.body = iframe1", "'Error: HierarchyRequestError: DOM Exception 3'");
+shouldThrow("document1.body = iframe1", "'HierarchyRequestError: A Node was inserted somewhere it doesn\\'t belong.'");
 shouldBe("iframe1.parentNode", "document.body");
 
-shouldThrow("document1.body = document1.createElement('iframe')", "'Error: HierarchyRequestError: DOM Exception 3'");
+shouldThrow("document1.body = document1.createElement('iframe')", "'HierarchyRequestError: A Node was inserted somewhere it doesn\\'t belong.'");
 
 document1.body = document.body;
 shouldBeTrue("document1.body != document.body");