Fixing Tech debt in ReleaseGold and Election (#3940)

* info.remainingValue is required to be zero

* Contract should be an account before doing any computation

* Change doc

* Update packages/protocol/contracts/governance/ReleaseGold.sol

Co-authored-by: Victor "Nate" Graf <victor@celo.org>

Co-authored-by: Victor "Nate" Graf <victor@celo.org>

packages/protocol/contracts/governance/Election.sol

@@ -1052,6 +1052,6 @@ contract Election is
       }
     }
     require(info.remainingValue == 0, "Failure to decrement all votes.");
-    return value.sub(info.remainingValue);
+    return value;
   }
 }

packages/protocol/contracts/governance/ReleaseGold.sol

@@ -426,15 +426,16 @@ contract ReleaseGold is UsingRegistry, ReentrancyGuard, IReleaseGold, Initializa
   /**
    * @notice Calculates remaining locked gold balance in the release schedule instance.
    *         The returned amount also includes pending withdrawals to maintain consistent releases.
+   *         Return 0 if address of caller is not an account.
    * @return The remaining locked gold of the release schedule instance.
    * @dev The returned amount may vary over time due to locked gold rewards.
    */
   function getRemainingLockedBalance() public view returns (uint256) {
-    uint256 pendingWithdrawalSum = 0;
     if (getAccounts().isAccount(address(this))) {
-      pendingWithdrawalSum = getLockedGold().getTotalPendingWithdrawals(address(this));
+      uint256 pendingWithdrawalSum = getLockedGold().getTotalPendingWithdrawals(address(this));
+      return getLockedGold().getAccountTotalLockedGold(address(this)).add(pendingWithdrawalSum);
     }
-    return getLockedGold().getAccountTotalLockedGold(address(this)).add(pendingWithdrawalSum);
+    return 0;
   }
 
   /**