Wei Yen

Results 3 issues of Wei Yen

Spec: https://facebook.github.io/graphql/#sec-Null-Value, https://facebook.github.io/graphql/#sec-Input-Values RFC: https://github.com/facebook/graphql/pull/83 `null` is now considered a valid input value. We should take steps to parse `null` as a proper literal.

Resolves #118

Just as how `field_asts` contains the descendants to be resolved after a resolver, it would be nice if the `ResolveInfo` object also contains the field ast's ancestors that leads to...