IntervalDomain display byte-sized integers as numbers
IntervalDomain display byte-sized integers as numbers

Summary:
When representing intervals over byte-sized integers, by default `operator<<`
interprets the bounds of the interval as characters, rather than integers.

This diff changes that -- even byte-sized integers are interpreted as integers.

Reviewed By: yuxuanchen1997

Differential Revision: D21039611

fbshipit-source-id: 7cb7f6e496f6050dc9cfd287a4f295da6e65a544

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