edit from @notwaldorf: From https://github.com/PolymerElements/paper-input/pull/296. Allows you to listen to the invalid event from the nested <input>, which is only triggered if checkValidity is called. Also, this makes sense since paper-input-container's _handleValueAndAutoValidate() also calls checkValidity, so there's no real reason why this shouldn't also.
edit from @notwaldorf: From https://github.com/PolymerElements/paper-input/pull/296. Allows you to listen to the
invalidevent from the nested<input>, which is only triggered ifcheckValidityis called. Also, this makes sense sincepaper-input-container's_handleValueAndAutoValidate()also callscheckValidity, so there's no real reason why this shouldn't also.