[Validator] Removed PHP <5.3.3 specific code which is not officially supported.

src/Symfony/Component/Validator/Constraints/EmailValidator.php

@@ -41,11 +41,6 @@ class EmailValidator extends ConstraintValidator
         if ($valid) {
             $host = substr($value, strpos($value, '@') + 1);
 
-            if (version_compare(PHP_VERSION, '5.3.3', '<') && strpos($host, '.') === false) {
-                // Likely not a FQDN, bug in PHP FILTER_VALIDATE_EMAIL prior to PHP 5.3.3
-                $valid = false;
-            }
-
             // Check for host DNS resource records
             if ($valid && $constraint->checkMX) {
                 $valid = $this->checkMX($host);