add xdomainmessenger to interface (#39)

* add xdomainmessenger to interface

* publish new version

packages/contracts/contracts/optimistic-ethereum/OVM/bridge/OVM_BaseCrossDomainMessenger.sol

@@ -18,7 +18,7 @@ contract OVM_BaseCrossDomainMessenger is iOVM_BaseCrossDomainMessenger {
     mapping (bytes32 => bool) public successfulMessages;
     mapping (bytes32 => bool) public sentMessages;
     uint256 public messageNonce;
-    address public xDomainMessageSender;
+    address override public xDomainMessageSender;
 
 
     /********************

packages/contracts/contracts/optimistic-ethereum/iOVM/bridge/iOVM_BaseCrossDomainMessenger.sol

@@ -6,6 +6,10 @@ pragma experimental ABIEncoderV2;
  * @title iOVM_BaseCrossDomainMessenger
  */
 interface iOVM_BaseCrossDomainMessenger {
+    /**********************
+     * Contract Variables *
+     **********************/
+    function xDomainMessageSender() external view returns (address);
 
     /********************
      * Public Functions *

packages/contracts/package.json

 {
   "name": "@eth-optimism/contracts",
-  "version": "0.0.2-alpha.4",
+  "version": "0.0.2-alpha.6",
   "main": "build/src/index.js",
   "files": [
     "build/**/*.js",