[appllo-server-koa]resolver function can not get context

[limerickgds]

Query: {
user(root, { id }, ctx) {
console.log(ctx);
},
}

ctx is ：

not koa.context

[limerickgds]

@evans

[duckywang1]

Related to #1392
// Please notice the following param -> 'context'
const server: ApolloServer = new ApolloServer({
typeDefs: xx,
resolvers: xx,
context: ({ ctx }) => ctx, // this is the key part
});

[limerickgds]

@duckywang1 ths