[Button]: Disabled ghost icon-only Button missing associated label

[zJag]

Environment

Browser

Chrome (others are probably effected)

Automated testing tool and ruleset

DAP Chrome Extension

Detailed description

What version of the Carbon Design System are you using?

v10.10.0

What did you expect to happen?

Using an icon-only ghost Button from carbon-components-react should not cause violations with DAP.

What happened instead?

When disabled, the button causes a violation with DAP stating the associated label is missing.

What WCAG 2.1 checkpoint does the issue violate?

Steps to reproduce the issue

1. Render an icon-only ghost button with proper props.
2. Disable the button.
3. Run the DAP extension

CodeSandbox

Additional information

• The styles introduced with fix(button): update icon only ghost button colors #5313 hides the assistive text tooltip when the button is a ghost button and is disabled.
• The icon within the button receives an aria-hidden attribute.
• Using W3C accessible name computation the button's name would be blank.

This could be fixed by not hiding the assistive text when the button is disabled (in carbon-components). This could also be fixed in carbon-components-react by ensuring the icon-only button receives an accessible name. For the latter, I was able to create a fix on my forked branch, and would be able to submit a PR if that's the proper solution.

[tw15egan]

Since the rest of the buttons still have the assistive text when disabled, we should just remove the styles that are specific to the ghost button. PR Incoming 🚀

https://github.com/carbon-design-system/carbon/pull/5313/files#diff-b73d9732aa1bfa4b943f188fdd4bfeccR228-R232