| Index: src/regexp.js | 
| diff --git a/src/regexp.js b/src/regexp.js | 
| index a574f62bf6a040b808bc40ea380f8a497f2261fe..44f8dd1234d9055afecd6be061839725b65f7d7d 100644 | 
| --- a/src/regexp.js | 
| +++ b/src/regexp.js | 
| @@ -278,6 +278,10 @@ function TrimRegExp(regexp) { | 
|  | 
|  | 
| function RegExpToString() { | 
| +  if (!IS_REGEXP(this)) { | 
| +    throw MakeTypeError('incompatible_method_receiver', | 
| +                        ['RegExp.prototype.toString', this]); | 
| +  } | 
| var result = '/' + this.source + '/'; | 
| if (this.global) result += 'g'; | 
| if (this.ignoreCase) result += 'i'; | 
|  |