Minor grammar fixes. (#9808)
* Minor grammar fixes.
* Update README.md
diff --git a/packages/flutter/README.md b/packages/flutter/README.md
index 1dc2a30..349f49a 100644
--- a/packages/flutter/README.md
+++ b/packages/flutter/README.md
@@ -2,7 +2,7 @@
=======
Flutter is a new way to build high-performance, cross-platform mobile apps.
-Flutter is optimized for today's, and tomorrow's, mobile devices. We are
+Flutter is optimized for today's — and tomorrow's — mobile devices. We are
focused on low-latency input and high frame rates on Android and iOS.
See the [getting started guide](https://flutter.io/getting-started/) for
