The Tor Browser / file revision

 // Copyright 2009 the Sputnik authors.  All rights reserved.

 // This code is governed by the BSD license found in the LICENSE file.

 /**

  * If Type(Primitive(x)) is not String and Type(Primitive(y)) is not String, then operator x + y returns ToNumber(x) + ToNumber(y)

  *

  * @path ch11/11.6/11.6.1/S11.6.1_A3.1_T2.4.js

  * @description Type(Primitive(x)) is different from Type(Primitive(y)) and both types vary between Boolean (primitive or object) and Undefined

  */

 //CHECK#1

 if (isNaN(true + undefined) !== true) {

   $ERROR('#1: true + undefined === Not-a-Number. Actual: ' + (true + undefined));

 }

 //CHECK#2

 if (isNaN(undefined + true) !== true) {

   $ERROR('#2: undefined + true === Not-a-Number. Actual: ' + (undefined + true));

 }

 //CHECK#3

 if (isNaN(new Boolean(true) + undefined) !== true) {

   $ERROR('#3: new Boolean(true) + undefined === Not-a-Number. Actual: ' + (new Boolean(true) + undefined));

 }

 //CHECK#4

 if (isNaN(undefined + new Boolean(true)) !== true) {

   $ERROR('#4: undefined + new Boolean(true) === Not-a-Number. Actual: ' + (undefined + new Boolean(true)));

 }