Sum of component.duration.preprolated for each component in components.
Example:
abjad> t = FixedDurationTuplet((2, 8), construct.scale(3))
abjad> print t.format
\times 2/3 {
c'8
d'8
e'8
}
abjad> durtools.sum_preprolated(t[:])
Rational(3, 8)