Reverty 1842 (see http://code.google.com/p/chromium/issues/detail?id=1717 )

src/date-delay.js

Index: src/date-delay.js
===================================================================
--- src/date-delay.js	(revision 1845)
+++ src/date-delay.js	(working copy)
@@ -1017,10 +1017,9 @@
   // Setup non-enumerable constructor property of the Date prototype object.
   %SetProperty($Date.prototype, "constructor", $Date, DONT_ENUM);
 
-  // Setup non-enumerable functions of the Date prototype object and set their
-  // names.  Use DONT_DELETE due to
-  // http://code.google.com/p/chromium/issues/detail?id=1717
-  InstallFunctions($Date.prototype, DONT_ENUM | DONT_DELETE, $Array(
+  // Setup non-enumerable functions of the Date prototype object and
+  // set their names.
+  InstallFunctions($Date.prototype, DONT_ENUM, $Array(
     "toString", DateToString,
     "toDateString", DateToDateString,
     "toTimeString", DateToTimeString,