Replace nonReentrant + refundFinalBalance with refundFinalBalanceNoReentry

contracts/utils/contracts/src/Refundable.sol

@@ -18,8 +18,12 @@
 
 pragma solidity ^0.5.9;
 
+import "./ReentrancyGuard.sol";
 
-contract Refundable {
+
+contract Refundable is
+    ReentrancyGuard
+{
 
     // This bool is used by the refund modifier to allow for lazily evaluated refunds.
     bool internal _shouldNotRefund;
@@ -29,6 +33,13 @@ contract Refundable {
         _refundNonZeroBalanceIfEnabled();
     }
 
+    modifier refundFinalBalanceNoReentry {
+        _lockMutexOrThrowIfAlreadyLocked();
+        _;
+        _refundNonZeroBalanceIfEnabled();
+        _unlockMutex();
+    }
+
     modifier disableRefundUntilEnd {
         if (_areRefundsDisabled()) {
             _;