Merge branch '2.8' into 3.4

* 2.8:
  Remove symfony/polyfill-ctype where not needed
  Use symfony/polyfill-ctype
  [Form] fixes instance variable phpdoc in FormRegistry class

Author: nicolas-grekas

composer.json

@@ -17,6 +17,7 @@
     ],
     "require": {
         "php": "^5.5.9|>=7.0.8",
+        "symfony/polyfill-ctype": "~1.8",
         "symfony/polyfill-mbstring": "~1.0",
         "symfony/translation": "~2.8|~3.0|~4.0"
     },