No need to check for PHP >= 7.0 anymore for persistent SSL.

Leaving assertParameters() for now but in general we should review how
connection backends are initialized to simplify things and remove some
protected methods, at least from base classes.

src/Connection/StreamConnection.php

@@ -58,11 +58,8 @@ class StreamConnection extends AbstractConnection
             case 'tcp':
             case 'redis':
             case 'unix':
-                break;
-
             case 'tls':
             case 'rediss':
-                $this->assertSslSupport($parameters);
                 break;
 
             default:
@@ -72,23 +69,6 @@ class StreamConnection extends AbstractConnection
         return $parameters;
     }
 
-    /**
-     * Checks needed conditions for SSL-encrypted connections.
-     *
-     * @param ParametersInterface $parameters Initialization parameters for the connection.
-     *
-     * @throws \InvalidArgumentException
-     */
-    protected function assertSslSupport(ParametersInterface $parameters)
-    {
-        if (
-            filter_var($parameters->persistent, FILTER_VALIDATE_BOOLEAN) &&
-            version_compare(PHP_VERSION, '7.0.0beta') < 0
-        ) {
-            throw new \InvalidArgumentException('Persistent SSL connections require PHP >= 7.0.0.');
-        }
-    }
-
     /**
      * {@inheritdoc}
      */