Explicitly set box-sizing of miniprompt close icon to content-box. (#1835)
Explicitly set box-sizing of miniprompt close icon to content-box. (#1835)

The current icon styles were written assuming a content-box box-sizing model, but 3p sites might have a style rule that sets box-sizing to border-box throughout the site (like Scenic does!).
subscriptions-project/swg-js,subscriptions-project/swg-js,subscriptions-project/swg-js