Revert "more experiements for cast"

This reverts commit ae1d1f8a0f1f1545076bd30b53ba5e8b1419a4c4.
Revert "add missing pieces for casting GDL"

This reverts commit 7df559df560a79c28a94f194e864365d3c5a50cd.
Revert "add support for casting GDL content"

This reverts commit c2c81f8301ee5e6b4e0c76337fd67a99ada3b5c0.