no need for the payable modifier in RootChain.startEnter()

[Jake-Song]

function startEnter(
    address _to,
    bytes32 _trieKey,
    bytes32 _trieValue
  )
    public
    payable
    returns (bool success)
  {
    uint requestId;
    uint weiAmount = msg.value;
    requestId = _storeRequest(EROs, ORBs, _to, weiAmount, _trieKey, _trieValue, false, false);
    numEnterForORB += 1;

    Data.Fork storage fork = forks[currentFork];

    emit RequestApplied(requestId, false);
    emit RequestCreated(requestId, msg.sender, _to, weiAmount, _trieKey, _trieValue, false, false);
    return true;
  }

There is no need of payable modifier in RootChain.startEnter() anymore because User who wants enter to Child chain have to enter with EtherToken to make PETH in Child chain.