Merge branch '5.0'

* 5.0: (36 commits)
  Add test for tagged iterator with numeric index
  Fix container lint command when a synthetic service is used in combination with the expression language
  Fix Travis script
  [Validator][Range] Fix typos
  [SecurityBundle] Minor fix in LDAP config tree builder
  [HttpClient] fix requests to hosts that idn_to_ascii() cannot handle
  Revert "minor #35559 [FrameworkBundle] remove mention of the old Controller class (nicolas-grekas)"
  [FrameworkBundle] remove redundant PHPDoc in console Descriptor and subclass
  [Mime] remove phpdoc mentioning Utf8AddressEncoder
  Add missing phpdoc
  Remove int return type from FlattenException::getCode
  [Yaml] fix dumping strings containing CRs
  [DI] Fix XmlFileLoader bad error message
  [Form] Handle false as empty value on expanded choices
  [Messenger] Add ext-redis min version req to tests
  Tweak message
  improve PlaintextPasswordEncoder docBlock summary
  [Validator] Add two missing translations for the Arabic (ar) locale
  Use some PHP 5.4 constants unconditionally
  Add new packages on the link script
  ...

Author: nicolas-grekas

HttpClientTrait.php

@@ -455,10 +455,7 @@ private static function parseUrl(string $url, array $query = [], array $allowedS
                 throw new InvalidArgumentException(sprintf('Unsupported IDN "%s", try enabling the "intl" PHP extension or running "composer require symfony/polyfill-intl-idn".', $host));
             }
 
-            if (false === $host = \defined('INTL_IDNA_VARIANT_UTS46') ? idn_to_ascii($host, IDNA_DEFAULT, INTL_IDNA_VARIANT_UTS46) : strtolower($host)) {
-                throw new InvalidArgumentException(sprintf('Unsupported host in "%s".', $url));
-            }
-
+            $host = \defined('INTL_IDNA_VARIANT_UTS46') ? idn_to_ascii($host, IDNA_DEFAULT, INTL_IDNA_VARIANT_UTS46) ?: strtolower($host) : strtolower($host);
             $host .= $port ? ':'.$port : '';
         }