Remove rocket-loader.min.js from Landing Pages

[n7studios]

Summary

Fixes this reported issue, where a Landing Page setup to redirect, and embedded in WordPress, won't redirect to the thank you page URL.

The redirect not being honored appears to be caused by including rocket-loader.min.js.

The Plugin fetches the landing page HTML, and then iterates through all scripts, checking if each src property is a fully qualified URL. If not (e.g. on landing pages, we find <script src="/cdn-cgi/scripts/7d0fa10a/cloudflare-static/rocket-loader.min.js" data-cf-settings="5756229aeeb7b4c76b79f093-|49" defer></script>), the Plugin will prepend the creator's URL (e.g. <script src="https://cheerful-architect-3237.ck.page/cdn-cgi/scripts/7d0fa10a/cloudflare-static/rocket-loader.min.js" data-cf-settings="c5d46ab73fb7b9b8aae27edf-|49" defer></script>) to ensure it can load the script on a WordPress Page that outputs the landing page HTML (otherwise, the relative path to the script won't work, because the landing page isn't hosted by ConvertKit here).

Removing this script allows the redirect to work, but I'm not understanding why, or whether this script can safely be removed by our WordPress Libraries / Plugins. If someone could let me know, we can then get this fixed.

Testing

• Updated unit tests to confirm rocket-loader.min.js is removed. The main WordPress Plugin will need its own PR to confirm the same when using this version of the WordPress Libraries.

Checklist

• I have written a test and included it in this PR
• I have run all tests and they pass
• The code passes when running the PHP CodeSniffer
• Code meets WordPress Coding Standards for PHP, HTML, CSS and JS
• Security and Sanitization requirements have been followed
• I have assigned a reviewer or two to review this PR (if you're not sure who to assign, we can do this step for you)

[noelherrick]

@n7studios Would this remove this rocket-loader for the entire page, including for pages that do not include a CK form? If so, we'll need to dig into this a bit more or perhaps allow the customer to disable it after giving a warning (I don't know if plugins can declare incompatibility with another plugin)

[n7studios]

@noelherrick This only removes rocket-loader from the ConvertKit form HTML that's fetched by this library. It doesn't remove anything from any WordPress Page. I'm still uncertain why it needs to be removed to get redirects working, though.

[noelherrick]

Ok, cool - yeah, I bet they're trying to be clever but it gets in the way of us doing something clever in our forms JS.