Twig ternary operator, Shorthand if-then-else

You can use shorthand syntax as of Twig 1.12.0

{{ foo ?: 'no' }} is the same as {{ foo ? foo : 'no' }}
{{ foo ? 'yes' }} is the same as {{ foo ? 'yes' : '' }}

{{ (ability.id in company_abilities) ? 'selected' : '' }}

The ternary operator is documented under 'other operators'