Fixed #33, update devDep

Author: Scrum

package.json

@@ -33,11 +33,11 @@
     "coveralls": "^2.11.8",
     "execa": "^0.2.2",
     "nyc": "^6.0.0",
-    "posthtml-custom-elements": "^1.0.2",
+    "posthtml-custom-elements": "^1.0.3",
     "path-exists": "^2.1.0",
     "read-pkg": "^1.1.0",
     "temp-write": "^2.1.0",
-    "xo": "^0.12.1"
+    "xo": "^0.13.0"
   },
   "posthtml": {
     "require": ["posthtml-custom-elements"]