* Revert "Add logging if FlutterDartProject fails to load the application kernel snapshot (#6257)" This reverts commit18ec58629e. * Revert "Update deprecated subtags from language subtag registry. (#6280)" This reverts commit6e159af6f2. * Revert "Add Xib splashscreen support (#6289)" This reverts commit9c2a3826c7. * Revert "Fix a compilation problem when using iPhoneOS12.0sdk(Xcode10) && clang version 7.0.0. (#6279)" This reverts commit911b381f71.