SkASSERT firing because pointer wraps negative.

Some pointers are being cast to intptr_t so they can be used with
SkAlign8(). However, a large pointer value might become a negative
integer since intptr_t is signed.

When comparing these intptr_ts, we expect the larger pointer value to be
greater. But it might be so large that it becomes negative, causing it
to be less than.

A SkASSERT is firing for this exact reason.

BUG=648452
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2353453004

Review-Url: https://codereview.chromium.org/2353453004
1 file changed