Fix issue 1447 by not redefining properties unneccesarily in seal and freeze.

src/v8natives.js

Index: src/v8natives.js
diff --git a/src/v8natives.js b/src/v8natives.js
index 3cb9dfd63e756f2e080596a586dbff80ccf673e3..0c88eb17a671e310aa2aa91ce02c2bba79d31f1f 100644
--- a/src/v8natives.js
+++ b/src/v8natives.js
@@ -938,7 +938,8 @@ function ObjectSeal(obj) {
   for (var i = 0; i < names.length; i++) {
     var name = names[i];
     var desc = GetOwnProperty(obj, name);
-    if (desc.isConfigurable()) desc.setConfigurable(false);
+    if (!desc.isConfigurable()) continue;
+    desc.setConfigurable(false);

[Lasse Reichstein, 2011/06/10 09:09:10]

Make it 
 if (desc.isConfigurable()) {
   ...
 }
instead of using continue. More readable, since it makes control flow visible by
indentation.

[Mads Ager (chromium), 2011/06/10 09:13:41]

Done.

     DefineOwnProperty(obj, name, desc, true);
   }
   return ObjectPreventExtension(obj);
@@ -954,6 +955,7 @@ function ObjectFreeze(obj) {
   for (var i = 0; i < names.length; i++) {
     var name = names[i];
     var desc = GetOwnProperty(obj, name);
+    if (!desc.isWritable() && !desc.isConfigurable()) continue;

[Lasse Reichstein, 2011/06/10 09:09:10]

Ditto here: invert the condition and put the rest of the loop inside the if. And
drop the tests before setting Writable and Configurable to false.

[Mads Ager (chromium), 2011/06/10 09:13:41]

Done.

     if (IsDataDescriptor(desc)) desc.setWritable(false);
     if (desc.isConfigurable()) desc.setConfigurable(false);
     DefineOwnProperty(obj, name, desc, true);