example 'block images' - fix typo and add other extensions (puppeteer…

…#334)

* fix typo and add extensions to example 'block images'

* fix code style, keep the newline at EOF

examples/block-images.js

@@ -22,7 +22,7 @@ const browser = await puppeteer.launch();
 const page = await browser.newPage();
 await page.setRequestInterceptionEnabled(true);
 page.on('request', request => {
-  if (/\.(png|jpg|jpeg$)/.test(request.url))
+  if (/\.(png|jpg|jpeg|gif|webp)$/.test(request.url))
     request.abort();
   else
     request.continue();