merged branch Adel-E/patch-1 (PR #4775)

Commits
-------

dbb63ae Fix typo change String to string

Discussion
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Fix typo change "String" to "string"

Bug fix: no
Feature addition: no
Backwards compatibility break: no
Symfony2 tests pass: yes
Fixes the following tickets: N/A
Todo: N/A
License of the code: MIT
Documentation PR: N/A

src/Symfony/Bundle/FrameworkBundle/HttpCache/HttpCache.php

@@ -32,7 +32,7 @@ abstract class HttpCache extends BaseHttpCache
      * Constructor.
      *
      * @param HttpKernelInterface $kernel   An HttpKernelInterface instance
-     * @param String              $cacheDir The cache directory (default used if null)
+     * @param string              $cacheDir The cache directory (default used if null)
      */
     public function __construct(HttpKernelInterface $kernel, $cacheDir = null)
     {