Potential regression: keyFields function called with normalized objects since 3.7.15

[phryneas]

Issue Description

It seems this happened with #10789 and was reported in Discord here:

https://discord.com/channels/1022972389463687228/1325644501976350881/1325644501976350881

Reproduction Steps

This test logs differently depending on version:

// in `policies.ts`
  it("`keyFields` function gets denormalized nested children", () => {
    const cache = new InMemoryCache({
      typePolicies: {
        Book: {
          keyFields(book, context) {
            console.log("keyFields", book);
            return ["isbn"];
          },
        },
      },
    });

    const bookQueryWithAuthorId = gql`
      query {
        book {
          title
          author {
            id
            name
          }
        }
      }
    `;

    const theInformationBookDataWithAuthorId = {
      __typename: "Book",
      isbn: "1400096235",
      title: "The Information",
      subtitle: "A History, a Theory, a Flood",
      author: {
        __typename: "Author",
        id: "123",
        name: "James Gleick",
      },
    };

    cache.writeQuery({
      query: bookQueryWithAuthorId,
      data: {
        book: theInformationBookDataWithAuthorId,
      },
    });

    expect(cache.extract(true)).toEqual({
      ROOT_QUERY: {
        __typename: "Query",
        book: {
          __ref: 'Book:{"isbn":"1400096235"}',
        },
      },
      "Author:123": {
        __typename: "Author",
        id: "123",
        name: "James Gleick",
      },
      'Book:{"isbn":"1400096235"}': {
        __typename: "Book",
        isbn: "1400096235",
        title: "The Information",
        author: { __ref: "Author:123" },
      },
    });
  });

Log pre-3.7.15:

  console.log
    keyFields {
      __typename: 'Book',
      isbn: '1400096235',
      title: 'The Information',
      subtitle: 'A History, a Theory, a Flood',
      author: { __typename: 'Author', id: '123', name: 'James Gleick' }
    }

Log from 3.7.15 on:

 console.log
    keyFields {
      __typename: 'Book',
      isbn: '1400096235',
      title: 'The Information',
      subtitle: 'A History, a Theory, a Flood',
      author: { __ref: 'Author:123' }
    }

      at keyFields (cache/inmemory/__tests__/policies.ts:366:21)
          at Map.forEach (<anonymous>)

Note the change here:

-      author: { __typename: 'Author', id: '123', name: 'James Gleick' }
+     author: { __ref: 'Author:123' }

Now this has been out for quite a while and it seems only one person was affected so far, so we'll have to weigh if it's possible to fix this while keeping the other bugfix in place.

This is mostly a tracking issue without a final call on that so far.

@apollo/client version

3.7.15 - present (3.12.x)