Changed SetPropertyPostInterceptor to climb the prototype chain to

src/objects.cc

Index: src/objects.cc
===================================================================
--- src/objects.cc	(revision 8993)
+++ src/objects.cc	(working copy)
@@ -1638,9 +1638,9 @@
     Object* value,
     PropertyAttributes attributes,
     StrictModeFlag strict_mode) {
-  // Check local property, ignore interceptor.
+  // Check local and prototype properties, ignore interceptor.
   LookupResult result;
-  LocalLookupRealNamedProperty(name, &result);
+  LookupRealNamedProperty(name, &result);
   if (result.IsFound()) {
     // An existing property, a map transition or a null descriptor was
     // found.  Use set property to handle all these cases.