Bug 953945 - Missing variable declaration in blist.js, r=florian

im/content/blist.js

@@ -169,7 +169,7 @@ buddyListContextMenu.prototype = {
     var logger = Components.classes["@instantbird.org/logger;1"]
                            .getService(Ci.ibILogger);
     var logs = [];
-    for (accountId in this.target.accounts) {
+    for (let accountId in this.target.accounts) {
       let account = this.target.accounts[accountId];
       for (let log in getIter(logger.getLogsForBuddy(account)))
         logs.push(log);