One more followup fix: __defineProperty__ should probably be global.

js/narcissus/jsexec.js

@@ -741,7 +741,9 @@ function Activation(f, a) {
 
 // Null Activation.prototype's proto slot so that Object.prototype.* does not
 // pollute the scope of heavyweight functions.  Also delete its 'constructor'
-// property so that id doesn't pollute function scopes.
+// property so that id doesn't pollute function scopes.  But first, we must
+// copy __defineProperty__ down from Object.prototype.
+Activation.prototype.__defineProperty__ = Object.prototype.__defineProperty__;
 Activation.prototype.__proto__ = null;
 delete Activation.prototype.constructor;