[BrowserKit] bugix: CookieJar returns cookies with domain "domain.com" f...

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | 
| License       | MIT
| Doc PR        | 

Fixes this bug:
```php
$cookieJar = new CookieJar();
$cookieJar->set(new Cookie('foo', 'bar', null, '/', '.example.com'));

print_r($cookieJar->allValues('http://wwwexample.com'));
// expected result: array()
// actual result: array('foo' => 'bar')
```