Fix scss lint errors
Fix scss lint errors

Disable the DuplicateProperty property linter in _shame.scss, to allow
the first property to override display: inline-block set by GOV.UK
elements for the polyfilled summary element. If FF supports
display:revert in the future, this will default to the browser’s styles
(also display: list-item).

alphagov/govuk_elements,alphagov/govuk_elements,alphagov/govuk_elements,gavboulton/govuk_elements,gavboulton/govuk_elements,joelanman/govuk_elements,joelanman/govuk_elements,gavboulton/govuk_elements,alphagov/govuk_elements,gavboulton/govuk_elements