Adding aria-labelledby attributes to the errors of a form eelement.

BasicForm.php

        $this->addElement(
            $this->createElement('password', 'mypassword')
                 ->setLabel('My Password')
                 ->setRequired(true)
        );

        $this->getElement('mypassword')
             ->getDecorator('errors')
             ->setOption('aria-labelledby', 'mypassword');