[12.x] Remove leftover method_exists checks

[rodrigopedra]

Once upon a time, in the distant land of Laravel 5.1, the Illuminate\Auth\AuthManager class still extended the Illuminate\Support\Manager class and had a common entry point to create drivers:

framework/src/Illuminate/Auth/AuthManager.php

Lines 16 to 36 in 7b586da

	protected function createDriver($driver)
	{
	$guard = parent::createDriver($driver);
	// When using the remember me functionality of the authentication services we
	// will need to be set the encryption instance of the guard, which allows
	// secure, encrypted cookie values to get generated for those cookies.
	if (method_exists($guard, 'setCookieJar')) {
	$guard->setCookieJar($this->app['cookie']);
	}
	if (method_exists($guard, 'setDispatcher')) {
	$guard->setDispatcher($this->app['events']);
	}
	if (method_exists($guard, 'setRequest')) {
	$guard->setRequest($this->app->refresh('request', $guard, 'setRequest'));
	}
	return $guard;
	}

As a generic entry point for an arbitrary Guard, the method_exists checks were necessary to properly configure a guard instance.

Many refactorings came, and the Illuminate\Auth\AuthManager evolved to a thing of its own, but the method_exists checks remained as a leftover from that distant past and ended up on a different method createSessionDriver() that does not create a generic instance anymore.

As we now create a concrete class, we know by fact which methods it has and don't need to check for their existence anymore.

This PR:

• Removes unnecessary method_exists() checks from the Illuminate\Auth\AuthManager@createSessionDriver() method