title: With contextIsolation = true, is it possible to use ipcRenderer?
body: <p>Here's my setup:</p>
  
  <p>Step 1. Create a preload.js file with the code:</p>
  
  <pre><code>window.ipcRenderer = require('electron').ipcRenderer;
  </code></pre>
  
  <p>Step 2. Preload this file in your main.js via webPreferences:</p>
  
  <pre><code>  mainWindow = new BrowserWindow({
      width: 800, 
      height: 600,
      webPreferences: {
        nodeIntegration: false,
        preload: __dirname + '/preload.js'
      }
    });
  </code></pre>
  
  <p>Step 3. In a renderer:</p>
  
  <pre><code>console.log(window.ipcRenderer); // Works!
  </code></pre>
  
  <p>Now following Electron's security guide, I wish to turn <code>contextIsolation=true</code>: <a href="https://electronjs.org/docs/tutorial/security#3-enable-context-isolation-for-remote-content" rel="noreferrer">https://electronjs.org/docs/tutorial/security#3-enable-context-isolation-for-remote-content</a></p>
  
  <p>Step 2bis.</p>
  
  <pre><code>  mainWindow = new BrowserWindow({
      width: 800, 
      height: 600,
      webPreferences: {
        contextIsolation: true,
        nodeIntegration: false,
        preload: __dirname + '/preload.js'
      }
    });
  </code></pre>
  
  <p>Step 3bis. In a renderer:</p>
  
  <p><code>console.log(window.ipcRenderer); // undefined</code></p>
  
  <p>Question: can I use <a href="https://electronjs.org/docs/api/ipc-renderer" rel="noreferrer">ipcRenderer</a> when <code>contextIsolation=true</code>?</p>