message: Fixing operation type of identity transform.
  Also simplifies the code.
diff: @@ -29,22 +29,9 @@ impl From<ExecutionJournal> for ExecutionEffect {
  let mut transforms = AdditiveMap::new();
  let journal: Vec<(Key, Transform)> = journal.into();
  for (key, transform) in journal.into_iter() {
  - if let Transform::Failure(_) = transform {
  - continue;
  - }
  - let op: Op = (&transform).into();
  - ops.insert_add(key, op);
  - transforms.insert_add(key, transform);
  - }
  -
  - Self { ops, transforms }
  - }
  -}
  -
  -impl From<&Transform> for Op {
  - fn from(transform: &Transform) -> Self {
  - match transform {
  - Transform::Identity => Op::NoOp,
  + let op = match transform {
  + Transform::Failure(_) => continue,
  + Transform::Identity => Op::Read,
  Transform::Write(_) => Op::Write,
  Transform::AddInt32(_)
  | Transform::AddUInt64(_)
  @@ -52,9 +39,11 @@ impl From<&Transform> for Op {
  | Transform::AddUInt256(_)
  | Transform::AddUInt512(_)
  | Transform::AddKeys(_) => Op::Add,
  -
  - // should be unreachable.
  - Transform::Failure(_) => Op::NoOp,
  + };
  + ops.insert_add(key, op);
  + transforms.insert_add(key, transform);
  }
  +
  + Self { ops, transforms }
  }
  }
  