// ASSERT(t->why_blocked != NotBlocked);
// Not true: for example,
// ASSERT(t->why_blocked != NotBlocked);
// Not true: for example,
// - the thread may have woken itself up already, because
// threadPaused() might have raised a blocked throwTo
// exception, see maybePerformBlockedException().
// - the thread may have woken itself up already, because
// threadPaused() might have raised a blocked throwTo
// exception, see maybePerformBlockedException().