Revert "Make window.undefined, window.NaN, window.Infinitiy read-only (ES5 section 15.1.1)"

src/v8natives.js

Index: src/v8natives.js
diff --git a/src/v8natives.js b/src/v8natives.js
index 3a2dd1f0e7b7d7826bd4b190d153f2d72327743c..9843635866323d5c5495edf0ffbdb9d12400f01e 100644
--- a/src/v8natives.js
+++ b/src/v8natives.js
@@ -162,14 +162,13 @@ function GlobalEval(x) {
 
 function SetupGlobal() {
   // ECMA 262 - 15.1.1.1.
-  %SetProperty(global, "NaN", $NaN, DONT_ENUM | DONT_DELETE | READ_ONLY);
+  %SetProperty(global, "NaN", $NaN, DONT_ENUM | DONT_DELETE);
 
   // ECMA-262 - 15.1.1.2.
-  %SetProperty(global, "Infinity", 1/0, DONT_ENUM | DONT_DELETE | READ_ONLY);
+  %SetProperty(global, "Infinity", 1/0, DONT_ENUM | DONT_DELETE);
 
   // ECMA-262 - 15.1.1.3.
-  %SetProperty(global, "undefined", void 0, 
-               DONT_ENUM | DONT_DELETE | READ_ONLY);
+  %SetProperty(global, "undefined", void 0, DONT_ENUM | DONT_DELETE);
 
   // Setup non-enumerable function on the global object.
   InstallFunctions(global, DONT_ENUM, $Array(