Revert "core: update DAO soft-fork number, clean up the code"

This reverts commit ba784bdf36.

core/execution.go

@@ -84,10 +84,12 @@ func exec(env vm.Environment, caller vm.ContractRef, address, codeAddr *common.A
 		address = &addr
 		createAccount = true
 	}
-	// Mark all contracts doing outbound value transfers to allow DAO filtering.
+
+	// mark the code hash if the execution is a call, callcode or delegate.
 	if value.Cmp(common.Big0) > 0 {
 		env.MarkCodeHash(env.Db().GetCodeHash(caller.Address()))
 	}
+
 	snapshotPreTransfer := env.MakeSnapshot()
 	var (
 		from = env.Db().GetAccount(caller.Address())
@@ -146,7 +148,7 @@ func execDelegateCall(env vm.Environment, caller vm.ContractRef, originAddr, toA
 		caller.ReturnGas(gas, gasPrice)
 		return nil, common.Address{}, vm.DepthError
 	}
-	// Mark all contracts doing outbound value transfers to allow DAO filtering.
+
 	if value.Cmp(common.Big0) > 0 {
 		env.MarkCodeHash(env.Db().GetCodeHash(caller.Address()))
 	}