Use a hardcoded no-op instead of instancing

The use of `new Function()` causes an EvalError if the environment's CSP
forbids execution of unsafe-eval. As there's no runtime evaluation being
performed, it's better to use a plain anonymous function instead.

lib/chai/utils/addProperty.js

@@ -36,7 +36,7 @@ var transferFlags = require('./transferFlags');
  */
 
 module.exports = function addProperty(ctx, name, getter) {
-  getter = getter === undefined ? new Function() : getter;
+  getter = getter === undefined ? function () {} : getter;
 
   Object.defineProperty(ctx, name,
     { get: function propertyGetter() {