Test common case first (#2023)

contracts/utils/Address.sol

@@ -29,7 +29,7 @@ library Address {
         bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
         // solhint-disable-next-line no-inline-assembly
         assembly { codehash := extcodehash(account) }
-        return (codehash != 0x0 && codehash != accountHash);
+        return (codehash != accountHash && codehash != 0x0);
     }
 
     /**