Placeholder issue for feedback on `@defer` & `@stream` proposal

Problem

For each release of GraphQL.js, we are now publishing an accompanying release containing an experimental implementation of the `@defer` and `@stream` directives. We are hoping to get community feedback on these releases before the proposal is accepted into the GraphQL specification. You can use this experimental release of GraphQL.js by adding the following to your project's package.json file. [code block] A similar release of `express-graphql` will be coming soon. I am creating this issue as a placeholder for anyone who has tried out these experimental packages to leave feedback. Please let us know if everything is working as expected or if you run into any issues. Any suggestions for improvements are also welcome. References: Demo repo Conference talk about defer/stream defer/stream RFC Spec edits graphql-js branch express-graphql PR graphql-over-http RFC fetch-multipart-graphql (client library) meros (client library) Feedback received so far Call `return` on iterable when connection closes Raised by @danielrearden `graphql-js` Fixed: https://github.com/graphql/graphql-js/pull/2843 Released: TBD `express-graphql` Fixed: https://github.com/graphql/express-graphql/pull/583/commits/ce8429e5c15172b394e65d5a27491611b5fb354e Released: `express-graphql@0.12.0-experimental-stream-defer.1` `content-length` in payload should not be required, parsers should use boundary instead Raised by @maraisr `graphql-over-http` spec Fixed: https://g