- Make read return 0 if readLength==0
- Return RESULT_END_OF_INPUT properly in the case that
bytesRemaining is unset (this was broken previously,
but only applies for assets > 2^31 bytes, so it's
unlikely anyone ever hit this issue)
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=135136541
