Revert "Remove computeValue.isSpecified"

This reverts commit 74e8ed99d0b6cca15d19d7d6d65960445cb7c152.

Reason for revert: Danny managed to reproduce a crash where the offset is unspecified, so apparently this code is still needed.

Change-Id: I53984a051ebb31cbeb4047eeb9d7bfd08584b768
1 file changed