intro_flutter_gpu: Enable master CI

Author: domesticmouse

flutter_ci_script_master.sh

@@ -27,8 +27,7 @@ declare -a CODELABS=(
   "haiku_generator"
   "homescreen_codelab"
   "in_app_purchases"
-  # TODO(domesticmouse): The protocol version of native_assets_cli-0.9.0 is 1.5.0, which is no longer supported.
-  # "intro_flutter_gpu"
+  "intro_flutter_gpu"
   "namer"
   "next-gen-ui"
   "testing_codelab"