style: format code with Prettier and remove unused code

Change-Id: I382f39d142cfa29f192447b0d2c6d48e113327b4
diff --git a/popup.html b/popup.html
index 51b6f97..b1eca61 100644
--- a/popup.html
+++ b/popup.html
@@ -1,9 +1,9 @@
-<!DOCTYPE html>
+<!doctype html>
 <html>
   <head>
-    <meta charset="UTF-8">
+    <meta charset="UTF-8" />
     <title>Report Webpages</title>
-    <link rel="stylesheet" type="text/css" href="popup.css">
+    <link rel="stylesheet" type="text/css" href="popup.css" />
   </head>
   <body>
     <div id="options">