Update dependency typescript to v3.3.1 (#444)

* Update dependency typescript to v3.3.1

* Fix trailing commas for function calls

* Reverting trailing comma change

* Avoiding trailing comma rule for imports

* I never know what the right thing to do is

* lockfile

src/index.ts

@@ -7,8 +7,7 @@ function init() {
 if (!('customElements' in self)) {
   import(
     /* webpackChunkName: "wc-polyfill" */
-    '@webcomponents/custom-elements',
-  ).then(init);
+    '@webcomponents/custom-elements').then(init);
 } else {
   init();
 }