aria-describedby connected to fieldset is not supported by screen readers

[Febakke]

When adding a description on fieldset, radiogroup, checkboxgroup it is added to the fieldset element using an aria-describedby. This is not standard HTML, and not well supported by browsers/screen readers.

Firefox and chrome/VoiceOver: Ignores description
Safari/VoiceOver: Overwrites all aria-descibedby inside the fieldset.

NVDA/chrome: Works as excpected

We have not yet tested with JAWS

[mimarz]

Relevant issue which is the basis for todays implementation: #519

[eirikbacker]

W3C actually mentions themselves that aria-describedby should not be used on non-interactive elements: https://www.w3.org/TR/using-aria/#label-support

I a fieldset has a related error message, the aria-describedby be set to all child inputs and point to the same message component. Note that the error message ID should then be placed before the ID pointing to the inputs individual description (aria-describedby="id-of-fieldset-error id-of-input-description" is well supported)