docs: fix fiddles (#39060)

* refactor: replace Array.prototype.forEach.call with plain for-of

* fix: add missing contextIsolation: false

* fix: open links in default browser

docs/fiddles/windows/manage-windows/frameless-window/renderer.js

@@ -1,4 +1,4 @@
-const { ipcRenderer } = require('electron')
+const { ipcRenderer, shell } = require('electron')
 
 const newWindowBtn = document.getElementById('frameless-window')
 
@@ -6,3 +6,15 @@ newWindowBtn.addEventListener('click', () => {
   const url = 'data:text/html,<h2>Hello World!</h2><a id="close" href="javascript:window.close()">Close this Window</a>'
   ipcRenderer.send('create-frameless-window', { url })
 })
+
+const links = document.querySelectorAll('a[href]')
+
+for (const link of links) {
+  const url = link.getAttribute('href')
+  if (url.indexOf('http') === 0) {
+    link.addEventListener('click', (e) => {
+      e.preventDefault()
+      shell.openExternal(url)
+    })
+  }
+}