fix(service-worker): registration failed on Safari (#31140)

Since Angular v8, and commit b3dda0e, `parseUrl()` can be called without
`relativeTo`, thus `new URL()` can be called with `relativeTo = undefined`.

Safari does not like it and the service worker registration fails:
```js
new URL('https://angular.io/') // OK
new URL('https://angular.io/', undefined) // TypeError
```

Closes #31061

PR Close #31140

packages/service-worker/worker/src/adapter.ts

@@ -53,7 +53,9 @@ export class Adapter {
    * Extract the pathname of a URL.
    */
   parseUrl(url: string, relativeTo?: string): {origin: string, path: string, search: string} {
-    const parsed = new URL(url, relativeTo);
+    // Workaround a Safari bug, see
+    // https://github.com/angular/angular/issues/31061#issuecomment-503637978
+    const parsed = !relativeTo ? new URL(url) : new URL(url, relativeTo);
     return {origin: parsed.origin, path: parsed.pathname, search: parsed.search};
   }
 

packages/service-worker/worker/testing/scope.ts

@@ -186,7 +186,7 @@ export class SwTestHarness implements ServiceWorkerGlobalScope, Adapter, Context
 
   parseUrl(url: string, relativeTo?: string): {origin: string, path: string, search: string} {
     const parsedUrl: URL = (typeof URL === 'function') ?
-        new URL(url, relativeTo) :
+        (!relativeTo ? new URL(url) : new URL(url, relativeTo)) :
         require('url').parse(require('url').resolve(relativeTo || '', url));
 
     return {