Upgrade to emotion v10

Summary: React 16 is not compatible with react-emotion 9 (it prints warnings, see also https://github.com/emotion-js/emotion/issues/644). So we should upgrade to 10.

Reviewed By: mweststrate

Differential Revision: D18905889

fbshipit-source-id: c00d2dbbadb1c08544632cb9bfcd63f2b1818a25

docs/tutorial/js-custom.md

@@ -120,7 +120,7 @@ class Card extends React.Component<{
     cursor: 'pointer',
   }));
 
-  static Image = styled('div')({
+  static Image = styled.div({
     backgroundSize: 'cover',
     width: '100%',
     paddingTop: '100%',