[Infrastructure] - Export src/infrastructure/platforms/platform.dart from the test lib (#2514)

Author: miguelcmedeiros

super_editor/lib/super_editor_test.dart

@@ -1,5 +1,6 @@
 library super_editor_test;
 
+export 'src/infrastructure/platforms/platform.dart';
 export 'src/test/ime.dart';
 export 'src/test/super_editor_test/supereditor_inspector.dart';
 export 'src/test/super_editor_test/supereditor_robot.dart';