- add new logic to ConvertForLoopOperation to store child
  ConvertForLoopOperations to handle nested cases
- in ConvertLoopFixCore while searching through for statements,
  set child for loop operations as created
- add new logic to ConvertIterableLoopOperation when replacing
  expressions with loop variable name so that any child for loops
  that have set their for-loop expression to the variable
- add new test to SaveParticipantTest

Change-Id: Ic5bfe7ecf33f35c991674d035f334e0589777c01