merged branch jakzal/domcrawler-missing-docblocks (PR symfony#9025)

This PR was merged into the 2.2 branch.

Discussion
----------

[DomCrawler] Added missing docblocks and removed redundant type in a return annotation

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Commits
-------

d414213 [DomCrawler] Added missing docblocks and removed unneeded return annotation.

src/Symfony/Component/DomCrawler/Crawler.php

@@ -84,8 +84,6 @@ public function add($node)
      *
      * @param string      $content A string to parse as HTML/XML
      * @param null|string $type    The content type of the string
-     *
-     * @return null|void
      */
     public function addContent($content, $type = null)
     {
@@ -710,6 +708,11 @@ public static function xpathLiteral($s)
         return sprintf("concat(%s)", implode($parts, ', '));
     }
 
+    /**
+     * @param integer $position
+     *
+     * @return \DOMElement|null
+     */
     private function getNode($position)
     {
         foreach ($this as $i => $node) {
@@ -723,6 +726,12 @@ private function getNode($position)
         // @codeCoverageIgnoreEnd
     }
 
+    /**
+     * @param \DOMElement $node
+     * @param string      $siblingDir
+     *
+     * @return array
+     */
     private function sibling($node, $siblingDir = 'nextSibling')
     {
         $nodes = array();