filter from graphql-anywhere removes __typename thus breaking cache updates.

[lifeiscontent]

Intended outcome:
filter from graphql-anywhere should filter everything thats not in the document, but also include __typename

Actual outcome:
__typename gets removed from the document, thus breaking the update function in a mutation when running cache.writeData({id: dataIdFromObject(object), data})

How to reproduce the issue:

1. grab a document that doesn't have __typename specified
2. run filter on it
3. notice __typename will be removed from data

Versions
System:
OS: macOS Mojave 10.14.6
Binaries:
Node: 10.16.3 - ~/n/bin/node
Yarn: 1.17.3 - ~/.yarn/bin/yarn
npm: 6.11.2 - /usr/local/bin/npm
Browsers:
Chrome: 77.0.3865.75
Firefox: 68.0
Safari: 13.0
npmPackages:
@apollo/react-common: 3.1.1 => 3.1.1
@apollo/react-components: 3.1.1 => 3.1.1
@apollo/react-hoc: 3.1.1 => 3.1.1
@apollo/react-hooks: 3.1.1 => 3.1.1
@apollo/react-ssr: 3.1.1 => 3.1.1
@apollo/react-testing: 3.1.1 => 3.1.1
apollo-cache: 1.3.2 => 1.3.2
apollo-cache-inmemory: 1.6.3 => 1.6.3
apollo-client: 2.6.4 => 2.6.4
apollo-link: 1.2.13 => 1.2.13
apollo-link-context: 1.0.19 => 1.0.19
apollo-link-error: 1.1.12 => 1.1.12
apollo-link-http: 1.5.16 => 1.5.16
apollo-utilities: 1.3.2 => 1.3.2

[lifeiscontent]

CC: @hwillson this is important.

[lifeiscontent]

It's a bit of an edge case, but if people can't use the mutationResult as the object to pass dataIdFromObject to getting data from the parent is a last resort.

[dylanwulf]

It looks like the graphql-anywhere package is getting removed in v3: #5159