Banner action loading state is broken (?)

[ben-che]

Issue summary

The loading state in the banner primary action doesn't seem to be working. From the docs it seems to be a valid prop we can pass to the banner component. However, the spinner doesn't seem to appear.

Let me know if this is an issue, or if I just read the docs wrong or did something wrong on my end. I'll be happy to submit a PR if this is a bug!

Expected behavior

A spinner should appear when the loading prop in the banner is set to true.

Actual behavior

There's no spinner 😢

Steps to reproduce the problem

I made a fork from the sandbox you provide us in the Polaris docs, and I just add a loading: true value to the Banner's action prop: https://codesandbox.io/s/bold-keldysh-pcfq0?file=/App.js

Reduced test case

The best way to get your bug fixed is to provide a reduced test case. This CodeSandbox template is a great starting point.

Specifications

• Are you using the React components? (Y/N): Yes
• Polaris version number: 5.8
• Browser: Chrome
• Device: Macbook pro
• Operating System: Catalina 10.15.7

Or run npx envinfo --system --binaries --browsers --npmPackages react,react-dom,@shopify/polaris to provide specifications on your environment including version numbers, browser, device, and operating system.

Paste the results here:

👋 Thanks for opening your first issue. A contributor should give feedback soon. If you haven’t already, please check out the contributing guidelines.