Simplify getHost by using the URL constructor

This patch removes the dependency on a dynamically-generated anchor
element just to get the origin of a given string representing a URL.

Change-Id: I3fdc9416da768ca44f168622538af191093cd804
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2535051Reviewed-by: Henrik Grunell <grunell@chromium.org>
Commit-Queue: Mathias Bynens <mathias@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827743}

chrome/browser/resources/hangout_services/thunk.js

@@ -20,17 +20,8 @@ chrome.runtime.onMessageExternal.addListener(function(
     if (!url) {
       return '';
     }
-    // Use the DOM to parse the URL. Since we don't add the anchor to
-    // the page, this is the only reference to it and it will be
-    // deleted once it's gone out of scope.
-    const a = document.createElement('a');
-    a.href = url;
-    let origin = a.protocol + '//' + a.hostname;
-    if (a.port != '') {
-      origin = origin + ':' + a.port;
-    }
-    origin = origin + '/';
-    return origin;
+    const origin = new URL(url).origin;
+    return `${origin}/`;
   }
 
   try {