merged branch danielholmes/patch-1 (PR #2008)

Commits
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e294211 [DomCrawler] Removed unused document property in Form

Discussion
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[DomCrawler] Removed unused document property in Form

src/Symfony/Component/DomCrawler/Form.php

@@ -22,7 +22,6 @@ use Symfony\Component\DomCrawler\Field\FormField;
  */
 class Form extends Link implements \ArrayAccess
 {
-    private $document;
     private $button;
     private $fields;