Post-Mutation Event checks must re-check document constraints.

LayoutTests/fast/dom/DOMException/prototype-object.html

Index: LayoutTests/fast/dom/DOMException/prototype-object.html
diff --git a/LayoutTests/fast/dom/DOMException/prototype-object.html b/LayoutTests/fast/dom/DOMException/prototype-object.html
index 84b22091ca840f9383b2f038944f606aeed585b5..f15cc301ec84c9f672d47f546c241ab7cc50072b 100644
--- a/LayoutTests/fast/dom/DOMException/prototype-object.html
+++ b/LayoutTests/fast/dom/DOMException/prototype-object.html
@@ -12,7 +12,7 @@ try {
   e = err;
 }
 
-shouldBeEqualToString("e.toString()", "HierarchyRequestError: Failed to execute 'appendChild' on 'Node': The new child element contains the parent.");
+shouldBeEqualToString("e.toString()", "HierarchyRequestError: Failed to execute 'appendChild' on 'Node': Nodes of type '#document' may not be inserted inside nodes of type '#document'.");
 shouldBeEqualToString("Object.prototype.toString.call(e)", "[object DOMException]");
 shouldBeEqualToString("Object.prototype.toString.call(e.__proto__)", "[object DOMExceptionPrototype]");
 shouldBeEqualToString("Object.prototype.toString.call(e.__proto__.__proto__)", "[object Error]");
@@ -24,6 +24,5 @@ shouldBe("e.HIERARCHY_REQUEST_ERR", "e.constructor.HIERARCHY_REQUEST_ERR");
 shouldBe("e.HIERARCHY_REQUEST_ERR", "3");
 shouldBe("e.code", "3");
 shouldBeEqualToString("e.name", "HierarchyRequestError");
-shouldBeEqualToString("e.message", "Failed to execute 'appendChild' on 'Node': The new child element contains the parent.");
-
+shouldBeEqualToString("e.message", "Failed to execute 'appendChild' on 'Node': Nodes of type '#document' may not be inserted inside nodes of type '#document'.");
 </script>