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

src/chrome/WelcomeScreen.tsx

@@ -29,7 +29,7 @@ const Container = styled(FlexColumn)({
   backgroundColor: colors.light02,
 });
 
-const Welcome = styled(FlexColumn)(({isMounted}: {isMounted?: boolean}) => ({
+const Welcome = styled(FlexColumn)<{isMounted?: boolean}>(({isMounted}) => ({
   width: 460,
   background: colors.white,
   borderRadius: 10,
@@ -85,7 +85,7 @@ const Icon = styled(Glyph)({
   marginLeft: 6,
 });
 
-const Logo = styled('img')({
+const Logo = styled.img({
   width: 128,
   height: 128,
   alignSelf: 'center',