Merge branch '4.0'

* 4.0:
  [2.7] Fix issues found by PHPStan
  [Command] Fix upgrade guide example
  Add php_unit_dedicate_assert to PHPCS
  [WebProfilerBundle] Let fetch() cast URL to string
  improve FormType::getType exception message details
  [Intl] Update ICU data to 60.2
  [Console] fix a bug when you are passing a default value and passing -n would ouput the index
  [FrameworkBundle] fix merge of 3.3 into 3.4
  bumped Symfony version to 4.0.3
  updated VERSION for 4.0.2
  updated CHANGELOG for 4.0.2
  bumped Symfony version to 3.4.3
  updated VERSION for 3.4.2
  updated CHANGELOG for 3.4.2

Author: nicolas-grekas

FormRegistry.php

@@ -82,11 +82,14 @@ public function getType($name)
 
             if (!$type) {
                 // Support fully-qualified class names
-                if (class_exists($name) && in_array('Symfony\Component\Form\FormTypeInterface', class_implements($name))) {
-                    $type = new $name();
-                } else {
-                    throw new InvalidArgumentException(sprintf('Could not load type "%s"', $name));
+                if (!class_exists($name)) {
+                    throw new InvalidArgumentException(sprintf('Could not load type "%s": class does not exist.', $name));
                 }
+                if (!is_subclass_of($name, 'Symfony\Component\Form\FormTypeInterface')) {
+                    throw new InvalidArgumentException(sprintf('Could not load type "%s": class does not implement "Symfony\Component\Form\FormTypeInterface".', $name));
+                }
+
+                $type = new $name();
             }
 
             $this->types[$name] = $this->resolveType($type);