Consuming a CLIEvent uses hidden closures, disallowing `base.Event`

Consuming an event creates a closure, requiring a `as self` reference. This doesn't seem necessary.

```fsharp
type A() =
[]
member val Event =
(new DelegateEvent()).Publish
type B() =
inherit A()
do base.Event.Add ignore // Error: 'base' values may only be used to make direct calls...
```

Even `let x = base.Event` is not allowed.

NOTE: the workaround is to use the implicit `add_Event` explicitly:

```fsharp
open System

type A() =
[]
member val Event =
(new DelegateEvent()).Publish
type B() =
inherit A()
do base.add_Event (fun _ _ -> ())
```