From cb06ffab5e31f012d64d46840400e12f9376adab Mon Sep 17 00:00:00 2001
From: "yangguo@chromium.org"
 <yangguo@chromium.org@ce2b1a6d-e550-0410-aec6-3dcde31c8c00>
Date: Fri, 18 May 2012 09:45:10 +0000
Subject: [PATCH] Correctly check for native error objects.

BUG=2138
TEST=

Review URL: https://chromiumcodereview.appspot.com/10392158

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11589 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
---
 src/messages.js | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/src/messages.js b/src/messages.js
index d813df9..ab71936 100644
--- a/src/messages.js
+++ b/src/messages.js
@@ -61,18 +61,21 @@ function FormatString(format, message) {
 
 
 // To check if something is a native error we need to check the
-// concrete native error types. It is not enough to check "obj
-// instanceof $Error" because user code can replace
-// NativeError.prototype.__proto__. User code cannot replace
-// NativeError.prototype though and therefore this is a safe test.
+// concrete native error types. It is not sufficient to use instanceof
+// since it possible to create an object that has Error.prototype on
+// its prototype chain. This is the case for DOMException for example.
 function IsNativeErrorObject(obj) {
-  return (obj instanceof $Error) ||
-      (obj instanceof $EvalError) ||
-      (obj instanceof $RangeError) ||
-      (obj instanceof $ReferenceError) ||
-      (obj instanceof $SyntaxError) ||
-      (obj instanceof $TypeError) ||
-      (obj instanceof $URIError);
+  switch (%_ClassOf(obj)) {
+    case 'Error':
+    case 'EvalError':
+    case 'RangeError':
+    case 'ReferenceError':
+    case 'SyntaxError':
+    case 'TypeError':
+    case 'URIError':
+      return true;
+  }
+  return false;
 }
 
 
-- 
2.7.4