fix-gravatar-alt.js

function crunchify_gravatar_alt( $crunchifyGravatar ) {
	if ( have_comments() ) {
		$alt = get_comment_author();
	}
	else {
		$alt = get_the_author_meta( 'display_name' );
	}
	$crunchifyGravatar = str_replace( 'alt=\'\'', 'alt=\'Avatar for ' . $alt . '\' title=\'Gravatar for ' . $alt . '\'', $crunchifyGravatar );
	return $crunchifyGravatar;
}
add_filter( 'get_avatar', 'crunchify_gravatar_alt' );