minor #7501 Replace array with null (cminovici)

This PR was submitted for the 3.2 branch but it was merged into the 2.7 branch instead (closes #7501).

Discussion
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Replace array with null

Argument 2 passed to Symfony\Component\BrowserKit\Client::__construct() must be an instance of Symfony\Component\BrowserKit\History or null, array given

Commits
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131722a Replace array with null

Author: xabbuh

components/browser_kit.rst

@@ -187,7 +187,7 @@ into the client constructor::
     $cookieJar = new Cookie('flavor', 'chocolate', strtotime('+1 day'));
 
     // create a client and set the cookies
-    $client = new Client(array(), array(), $cookieJar);
+    $client = new Client(array(), null, $cookieJar);
     // ...
 
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