fix: Check if cookies are iterable before iterating

[das-peter]

It can happen that the returned value is not iterable. The geetAllCookies() methode also declares the its return as "mixed".
Just about having slightly more defensive code.

[codecov]

Codecov Report

Merging #356 (f387514) into master (e5f8421) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##             master     #356      +/-   ##
============================================
+ Coverage     90.02%   90.04%   +0.02%     
- Complexity      150      151       +1     
============================================
  Files             1        1              
  Lines           421      422       +1     
============================================
+ Hits            379      380       +1     
  Misses           42       42              

Impacted Files	Coverage Δ
src/Selenium2Driver.php	90.04% <100.00%> (+0.02%)	⬆️

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[stof]

In which case does this happen ?

[das-peter]

I had a request to wd/hub/session/chrome-100-0-4896-75-1-bc5dc535-0653-4f64-814c-d172db4c1582/session/bed6779a89bb52104cef11e83d40d7e6/cookie return null as value.
Underlying library is instaclick/php-webdriver - \WebDriver\Session::getAllCookies() which just passes the value as received from the endpoint back to the consumer.
It is highly likely this is / was an error on the endpoint but I don't think this warrants a generic failure.