Simplify the computation of CAPMIN
CAPMIN is the largest min-content contribution of the table captions.
In Servo, the standard way to compute min/max-content contributions is
outer_inline_content_sizes(), so just use that instead of reinventing
the wheel.
This also fixes cyclic percentages to resolve consistently with normal
block boxes.
Signed-off-by: Oriol Brufau obrufau@igalia.com