add test task

package.json

@@ -4,7 +4,7 @@
   "scripts": {
     "start": "webpack -w --debug",
     "lint": "eslint src",
-    "test": "true"
+    "test": "karma start"
   },
   "repository": {
     "type": "git",

src/background/index.js

@@ -2,7 +2,7 @@ import * as actions from '../shared/actions';
 import * as tabs from './tabs';
 import KeyQueue from './key-queue';
 
-const queue = new KeyQueue(KeyQueue.DEFAULT_KEYMAP);
+const queue = new KeyQueue();
 
 const keyDownHandle = (request) => {
   return queue.push({