Add some stuff that requires transpilation. (#4174)

packages/react-scripts/fixtures/monorepos/packages/comp1/index.js

@@ -1,5 +1,21 @@
 import React from 'react';
 
-const Comp1 = () => <div>Comp1</div>;
+class Comp1 extends React.Component {
+  static parts = {
+    greeting: 'hello',
+    region: 'world',
+  };
+
+  render() {
+    const { greeting, region } = Comp1.parts;
+
+    return (
+      <div {...this.props}>
+        Comp1
+        {greeting} {region}
+      </div>
+    );
+  }
+}
 
 export default Comp1;