Merge branch '4.0'

* 4.0:
  Remove symfony/polyfill-ctype where not needed
  Use symfony/polyfill-ctype
  [Form] fixes instance variable phpdoc in FormRegistry class
  bumped Symfony version to 4.0.10
  updated VERSION for 4.0.9
  updated CHANGELOG for 4.0.9
  bumped Symfony version to 3.4.10
  updated VERSION for 3.4.9
  updated CHANGELOG for 3.4.9

Author: nicolas-grekas

composer.json

@@ -17,6 +17,7 @@
     ],
     "require": {
         "php": "^7.1.3",
+        "symfony/polyfill-ctype": "~1.8",
         "symfony/polyfill-mbstring": "~1.0",
         "symfony/translation": "~3.4|~4.0"
     },