message: give Avatar COMMON props
diff: import PropTypes from 'prop-types'
  import styled from 'styled-components'
  -import {get} from './constants'
  +import {get, COMMON} from './constants'
  import {space} from 'styled-system'
  import systemPropTypes from '@styled-system/prop-types'
  import theme from './theme'
  @@ -24,7 +24,7 @@ const Avatar = styled.img.attrs(props => ({
  line-height: ${get('lineHeights.condensedUltra')};
  vertical-align: middle;
  border-radius: ${props => getBorderRadius(props)};
  - ${space};
  + ${COMMON};
  `
  Avatar.defaultProps = {
  @@ -35,10 +35,10 @@ Avatar.defaultProps = {
  }
  Avatar.propTypes = {
  - alt: PropTypes.string.isRequired,
  + alt: PropTypes.string,
  + ...COMMON.propTypes,
  size: PropTypes.number,
  src: PropTypes.string,
  - ...systemPropTypes.space,
  square: PropTypes.bool,
  theme: PropTypes.object
  }
  