- see commit 9d5364c
- never correct to pass a `Func<object>` to `GetExplorerForExpression()`
- `<label/>` tests succeeded because that tag helper doesn't use expression result
- `<select/>` tests succeeded because that tag helper gets result from `ViewData`
- does not use `ModelExplorer` due to #1468
nit: update variable names `metadata` -> `modelExplorer`
28561e9924