migration: update migrated withdrawal gas limit

More accurately computes the gas limit for a migrated
withdrawal. This is useful to prevent the gaslimit
for large transactions from going over the consensus
level block gas limit. It is unlikely for a transaction
to go over the block gas limit, but this is a preventative
fix just in case.

.changeset/poor-buses-hug.md

+---
+'@eth-optimism/sdk': patch
+---
+
+Update migrated withdrawal gaslimit calculation

op-chain-ops/crossdomain/migrate.go

@@ -11,6 +11,7 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/params"
 )
 
 var (
@@ -82,8 +83,18 @@ func MigrateWithdrawal(withdrawal *LegacyWithdrawal, l1CrossDomainMessenger *com
 		return nil, fmt.Errorf("cannot abi encode relayMessage: %w", err)
 	}
 
+	// Compute the cost of the calldata
+	dataCost := uint64(0)
+	for _, b := range data {
+		if b == 0 {
+			dataCost += params.TxDataZeroGas
+		} else {
+			dataCost += params.TxDataNonZeroGasEIP2028
+		}
+	}
+
 	// Set the outer gas limit. This cannot be zero
-	gasLimit := uint64(len(data)*16 + 200_000)
+	gasLimit := dataCost + 200_000
 
 	w := NewWithdrawal(
 		versionedNonce,

packages/sdk/src/cross-chain-messenger.ts

@@ -18,16 +18,15 @@ import {
   sleep,
   remove0x,
   toHexString,
-  fromHexString,
   toRpcHexString,
   hashCrossDomainMessage,
   encodeCrossDomainMessageV0,
   encodeCrossDomainMessageV1,
-  L2OutputOracleParameters,
   BedrockOutputData,
   BedrockCrossChainMessageProof,
   decodeVersionedNonce,
   encodeVersionedNonce,
+  calldataCost,
 } from '@eth-optimism/core-utils'
 import { getContractInterface, predeploys } from '@eth-optimism/contracts'
 import * as rlp from 'rlp'
@@ -352,12 +351,13 @@ export class CrossChainMessenger {
       }
     }
 
-    const minGasLimit = fromHexString(resolved.message).length * 16 + 200_000
+    const dataCost = calldataCost(resolved.message)
+    const minGasLimit = dataCost.add(200_000)
 
     return {
       ...resolved,
       value,
-      minGasLimit: BigNumber.from(minGasLimit),
+      minGasLimit,
       messageNonce: encodeVersionedNonce(
         BigNumber.from(1),
         resolved.messageNonce