Automatically merged updates to draft EIP(s) 1884 (#2239)

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 - It only modifies existing Draft or Last Call EIP(s)
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EIPS/eip-1884.md

@@ -114,7 +114,14 @@ I expect that certain patterns will be less used, for example the use of multipl
 
 ## Test Cases
 
-No test cases are implemented as of yet.
+Testcases that should be implemented: 
+- Test that `selfbalance == balance(address)`, 
+- Test that `balance(this)` costs as before, 
+- Test that `selfbalance` does not pop from stack
+- Gascost verification of `SLOAD`, `EXTCODEHASH` and `SELFBALANCE`
+- Verify that `SELFBALANCE` is invalid before Istanbul
+
+Some testcases have been implemented as statetests at https://github.com/holiman/IstanbulTests/tree/master/GeneralStateTests
 
 ## Implementation
 
@@ -139,6 +146,7 @@ func opSelfBalance(pc *uint64, interpreter *EVMInterpreter, contract *Contract,
 - See backwards compatibility section. 
 - There are no special edgecases regarding `SELFBALANCE`, if we define it as `BALANCE` with `address` instead of popping an address from the stack -- since `BALANCE` is already well-defined.
 - It should be investigated if Solidity contains any hardcoded expectations on the gas cost of these operations.
+- In many cases, a recipient of `ether` from a `CALL` will want to issue a `LOG`. The `LOG` operation costs `375` plus `375` per topic. If the `LOG` also wants to do an `SLOAD`, this change may make some such transfers fail. 
 
 ## Copyright
 Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).