Copy script tag list by slicing

Same issue as #186 but for executeScriptTags.  Didn't originally think this was necessary since the number of scripts on the page isn't directly changed by each iteration of the loop, but I ran into a scenario where it's indirectly changed:

```html
<body>
   <div id="container">
      <script>
      $('#container').html("content");
      </script>
   </div>
   <script>
   // another script
   </script>
</body>
```

If there are multiple scripts on the page and any of them except the last one remove or overwrite themselves, executeScriptTags will throw an error.