DOMException toString is not correct

LayoutTests/fast/mediastream/script-tests/argument-types.js

 description("Tests the acceptable types for arguments to navigator.getUserMedia methods.");
 
 function test(expression, expressionShouldThrow, expectedException) {
     if (expressionShouldThrow) {
         if (expectedException)
             shouldThrow(expression, '"' + expectedException + '"');
         else
             shouldThrow(expression, '"TypeError: Not enough arguments"');
     } else {
         shouldNotThrow(expression);
     }
 }
 
-var notSupportedError = new Error('NotSupportedError: DOM Exception 9');
+var notSupportedError = 'NotSupportedError: The implementation did not support the requested type of object or operation.';
 var typeError = new TypeError('Type error');
 var typeNotAnObjectError = new TypeError('Not an object.');
 
 var emptyFunction = function() {};
 
 // No arguments
 test('navigator.webkitGetUserMedia()', true);
 
 // 1 Argument (getUserMedia requires at least 2 arguments).
 test('navigator.webkitGetUserMedia(undefined)', true);
@@ skipping 33 matching lines @@
 test('navigator.webkitGetUserMedia({audio:true}, emptyFunction, undefined)', false);
 test('navigator.webkitGetUserMedia({video: true}, emptyFunction, "video")', true, typeError);
 test('navigator.webkitGetUserMedia({video: true}, emptyFunction, null)', false );
 test('navigator.webkitGetUserMedia({video: true}, emptyFunction, {})', true, typeError);
 test('navigator.webkitGetUserMedia({video: true}, emptyFunction, true)', true, typeError);
 test('navigator.webkitGetUserMedia({video: true}, emptyFunction, 42)', true, typeError);
 test('navigator.webkitGetUserMedia({video: true}, emptyFunction, Infinity)', true, typeError);
 test('navigator.webkitGetUserMedia({video: true}, emptyFunction, -Infinity)', true, typeError);
 
 window.jsTestIsAsync = false;