Disallow compose navbar from being shrunk

app/assets/javascripts/components/features/compose/components/navigation_bar.jsx

@@ -16,7 +16,7 @@ const NavigationBar = React.createClass({
 
   render () {
     return (
-      <div style={{ padding: '10px', display: 'flex', cursor: 'default' }}>
+      <div style={{ padding: '10px', display: 'flex', flexShrink: '0', cursor: 'default' }}>
         <Permalink href={this.props.account.get('url')} to={`/accounts/${this.props.account.get('id')}`} style={{ textDecoration: 'none' }}><Avatar src={this.props.account.get('avatar')} size={40} /></Permalink>
 
         <div style={{ flex: '1 1 auto', marginLeft: '8px', color: '#9baec8' }}>