Add platform info maker fn for fragment spread

Reviewed By: mjmahone

Differential Revision: D76785553

fbshipit-source-id: e75b29bc407c90c225fdac15d43b17c80da5d6f8

Author: janettec

compiler/crates/graphql-ir/src/ir.rs

@@ -51,6 +51,13 @@ pub enum ExecutableDefinition {
 }
 
 impl ExecutableDefinition {
+    pub fn directives(&self) -> &[Directive] {
+        match self {
+            ExecutableDefinition::Operation(node) => &node.directives,
+            ExecutableDefinition::Fragment(node) => &node.directives,
+        }
+    }
+
     pub fn has_directive(&self, directive_name: DirectiveName) -> bool {
         match self {
             ExecutableDefinition::Operation(node) => node