change into spec directory before running standard

package.json

@@ -24,7 +24,7 @@
     "bootstrap": "python ./script/bootstrap.py",
     "build": "python ./script/build.py -c D",
     "lint": "npm run lint-js && npm run lint-cpp",
-    "lint-js": "standard && standard spec",
+    "lint-js": "standard && cd spec && standard",
     "lint-cpp": "python ./script/cpplint.py",
     "preinstall": "node -e 'process.exit(0)'",
     "repl": "python ./script/start.py --interactive",