When executing a @client query, result is not filtered to the selection set

**Intended outcome:**
Execute a `@client` query against local resolvers from GraphiQL and see in the result only the fields asked for in the query.

**Actual outcome:**
The entire object as returned by the local resolver is displayed

**How to reproduce the issue:**

Create a local resolver to implement

```
type Query {
foo: Bar
}

type Bar {
a: int
b: int
}
```

Execute query in GraphiQL

```
query {
foo {
a
}
}
```

You will see both `a` and `b` fields returned in the result pane, instead of just `a`.

Note that the Apollo client itself does _not_ suffer from this problem - that is, in code the result emitted by the observable will be correctly filtered based on the selection set.

This issue makes giving demos/trainings to show the flexible nature of GQL particularly frustrating.

**Desktop (please complete the following information):**
- OS: Mac BIg Sur
- Browser Chrome
- Chrome version: 89.0.4389.90
- Extension version: 3.0.2