fix: arbitrum chain id check in all ChainSpecificUtil methods (#10756)

* fix: arbitrum chain id check in all CSU methods

The arbitrum chain id check needs to be the same in all of the methods
exported in the ChainSpecificUtil contract. Prior to this change
getBlockNumber, getCurrentTxL1GasFees and getL1CalldataGasCost did not
correctly check for all possible arbitrum chain ids.

To prevent this kind of error in the future, a new private function
isArbitrumChainId was created and used in all methods that need to check
the chain id.

* chore: prettier

contracts/src/v0.8/ChainSpecificUtil.sol

@@ -18,11 +18,7 @@ library ChainSpecificUtil {
 
   function getBlockhash(uint64 blockNumber) internal view returns (bytes32) {
     uint256 chainid = block.chainid;
-    if (
-      chainid == ARB_MAINNET_CHAIN_ID ||
-      chainid == ARB_GOERLI_TESTNET_CHAIN_ID ||
-      chainid == ARB_SEPOLIA_TESTNET_CHAIN_ID
-    ) {
+    if (isArbitrumChainId(chainid)) {
       if ((getBlockNumber() - blockNumber) > 256 || blockNumber >= getBlockNumber()) {
         return "";
       }
@@ -33,15 +29,15 @@ library ChainSpecificUtil {
 
   function getBlockNumber() internal view returns (uint256) {
     uint256 chainid = block.chainid;
-    if (chainid == ARB_MAINNET_CHAIN_ID || chainid == ARB_GOERLI_TESTNET_CHAIN_ID) {
+    if (isArbitrumChainId(chainid)) {
       return ARBSYS.arbBlockNumber();
     }
     return block.number;
   }
 
   function getCurrentTxL1GasFees() internal view returns (uint256) {
     uint256 chainid = block.chainid;
-    if (chainid == ARB_MAINNET_CHAIN_ID || chainid == ARB_GOERLI_TESTNET_CHAIN_ID) {
+    if (isArbitrumChainId(chainid)) {
       return ARBGAS.getCurrentTxL1GasFees();
     }
     return 0;
@@ -53,12 +49,22 @@ library ChainSpecificUtil {
    */
   function getL1CalldataGasCost(uint256 calldataSizeBytes) internal view returns (uint256) {
     uint256 chainid = block.chainid;
-    if (chainid == ARB_MAINNET_CHAIN_ID || chainid == ARB_GOERLI_TESTNET_CHAIN_ID) {
+    if (isArbitrumChainId(chainid)) {
       (, uint256 l1PricePerByte, , , , ) = ARBGAS.getPricesInWei();
       // see https://developer.arbitrum.io/devs-how-tos/how-to-estimate-gas#where-do-we-get-all-this-information-from
       // for the justification behind the 140 number.
       return l1PricePerByte * (calldataSizeBytes + 140);
     }
     return 0;
   }
+
+  /**
+   * @notice Return true if and only if the provided chain ID is an Arbitrum chain ID.
+   */
+  function isArbitrumChainId(uint256 chainId) internal pure returns (bool) {
+    return
+      chainId == ARB_MAINNET_CHAIN_ID ||
+      chainId == ARB_GOERLI_TESTNET_CHAIN_ID ||
+      chainId == ARB_SEPOLIA_TESTNET_CHAIN_ID;
+  }
 }