Enable eslint-plugin-custom-elements

Author: koddsson

.eslintrc.json

@@ -1,10 +1,16 @@
 {
   "root": true,
+  "plugins": ["custom-elements"],
   "extends": [
     "plugin:github/recommended",
     "plugin:github/browser",
-    "plugin:github/typescript"
+    "plugin:github/typescript",
+    "plugin:custom-elements/recommended"
   ],
+  "rules": {
+    "custom-elements/file-name-matches-element": ["error", {"suffix": "Element"}],
+    "custom-elements/tag-name-matches-class": ["error", {"suffix": "Element"}]
+  },
   "globals": {
     "CustomElementElement": "readonly"
   }