The Tor Browser / file revision

 // When we assign to a property that a proxy claims is inherited, the

 // defineProperty handler call to create the new own property should get

 // the newly assigned value.

 var hits;

 var handlers = {

   getOwnPropertyDescriptor: function(name) {

     return undefined;

   },

   getPropertyDescriptor: function(name) {

     return { value:42, writable:true, enumerable:true, configurable:true };

   },

   defineProperty: function(name, descriptor) {

     hits++;

     assertEq(name, 'x');

     assertEq(descriptor.value, 43);

   }

 };

 hits = 0;

 Proxy.create(handlers).x = 43;

 assertEq(hits, 1);