- The corresponding Razor change results in `HelperResult`s being rendered with async lambdas.
- This change enables `TagHelper`s and other async code to exist inside of `HelperResult` blocks.
- Added test to validate Templates (they generate `HelperResult`s) can utilize `TagHelper`s correctly.
- Rename `RazorPage`s `RenderBodyDelegate` to `RenderBodyDelegateAsync`.
aspnet/Razor#494