[RFC] Type condition optional on inline fragments.

Originally proposed by @josephsavona, this allows inline fragments to omit a type condition and thus always be considered for inclusion. If a type condition is omitted, no type refinement is done to the contained fields.

This enables a new kind of usecase where the only purpose for using an inline fragment is applying a directive to a grouping of fields:

```graphql
fragment Foo on Type {
  fieldA
  fieldB
  ... @include(if: $wat) {
    fieldC
    fieldD
  }
}
```

spec/Appendix B -- Grammar Summary.md

@@ -113,13 +113,13 @@ Argument : Name : Value
 
 FragmentSpread : ... FragmentName Directives?
 
-InlineFragment : ... on TypeCondition Directives? SelectionSet
+InlineFragment : ... TypeCondition? Directives? SelectionSet
 
-FragmentDefinition : fragment FragmentName on TypeCondition Directives? SelectionSet
+FragmentDefinition : fragment FragmentName TypeCondition Directives? SelectionSet
 
 FragmentName : Name but not `on`
 
-TypeCondition : NamedType
+TypeCondition : on NamedType
 
 Value[Const] :
   - [~Const] Variable

spec/Section 2 -- Language.md

@@ -431,7 +431,7 @@ otherwise the field's name.
 
 FragmentSpread : ... FragmentName Directives?
 
-FragmentDefinition : fragment FragmentName on TypeCondition Directives? SelectionSet
+FragmentDefinition : fragment FragmentName TypeCondition Directives? SelectionSet
 
 FragmentName : Name but not `on`
 
@@ -519,7 +519,7 @@ produce the same response object.
 
 #### Type Conditions
 
-TypeCondition : NamedType
+TypeCondition : on NamedType
 
 Fragments must specify the type they apply to. In this example, `friendFields`
 can be used in the context of querying a `User`.
@@ -578,7 +578,7 @@ will be present and `friends` will not.
 
 #### Inline Fragments
 
-InlineFragment : ... on TypeCondition Directives? SelectionSet
+InlineFragment : ... TypeCondition? Directives? SelectionSet
 
 Fragments can be defined inline within a selection set. This is done to
 conditionally include fields based on their runtime type. This feature of
@@ -603,6 +603,24 @@ query inlineFragmentTyping {
 }
 ```
 
+Inline fragments may also be used to apply a directive to a group of fields.
+If the TypeCondition is omitted, an inline fragment is considered to be of the
+same type as the enclosing context.
+
+```graphql
+query inlineFragmentNoType($expandedInfo: Boolean) {
+  user(handle: "zuck") {
+    id
+    name
+    ... @include(if: $expandedInfo) {
+      firstName
+      lastName
+      birthday
+    }
+  }
+}
+```
+
 
 ### Input Values
 

spec/Section 5 -- Validation.md

@@ -650,6 +650,12 @@ fragment inlineFragment on Dog {
     name
   }
 }
+
+fragment inlineFragment on Dog {
+  ... @include(if: true) {
+    name
+  }
+}
 ```
 
 and the following do not validate:

spec/Section 6 -- Execution.md

@@ -77,7 +77,7 @@ CollectFields(objectType, selectionSet, visitedFragments):
         * Append all items in {fragmentGroup} to {groupForResponseKey}.
     * If {selection} is an inline fragment:
       * Let {fragmentType} be the type condition on {selection}.
-      * If {doesFragmentTypeApply(objectType, fragmentType)} is false, continue
+      * If {fragmentType} is not {null} and {doesFragmentTypeApply(objectType, fragmentType)} is false, continue
         with the next {selection} in {selectionSet}.
       * Let {fragmentSelectionSet} be the top-level selection set of {selection}.
       * Let {fragmentGroupedFields} be the result of calling {CollectFields(objectType, fragmentSelectionSet)}.