title: puppeteer: Get base64 encoded image without separate download
body: <p>On a page that does not support downloading images or opening them in new tab, I can use the Chrome Developer (Tools->Network) to right click the image and do "copy image as URI".</p>
  
  <p>Is it possible to do the same with puppeteer?</p>
  
  <p>I tried to use few Node.js modules that are intended to convert an image to its base64 representation but they all seem to download the image and then return base64 representation.</p>