Add dynamic import transformer for dependencies in test env (facebook#5110)

Author: lixiaoyan

packages/babel-preset-react-app/dependencies.js

@@ -107,6 +107,9 @@ module.exports = function(api, opts) {
       ],
       // Adds syntax support for import()
       require('@babel/plugin-syntax-dynamic-import').default,
+      isEnvTest &&
+        // Transform dynamic import to require
+        require('babel-plugin-transform-dynamic-import').default,
     ].filter(Boolean),
   };
 };