Closes webpack dev server and exits process on "end" stdin

Author: kelseyleftwich

packages/react-scripts/scripts/start.js

@@ -152,6 +152,12 @@ checkBrowsers(paths.appPath, isInteractive)
         process.exit();
       });
     });
+
+    process.stdin.on('end', function() {
+      devServer.close();
+      process.exit();
+    });
+    process.stdin.resume();
   })
   .catch(err => {
     if (err && err.message) {