Initial support for GraphQL ObjectTypeDefinition (prettier#2305)

It appears in some files inside of fb codebase

src/printer-graphql.js

@@ -209,6 +209,21 @@ function genericPrint(path, options, print) {
       ]);
     }
 
+    case "ObjectTypeDefinition": {
+      return concat([
+        "type ",
+        path.call(print, "name"),
+        " = {",
+        indent(concat([hardline, join(hardline, path.map(print, "fields"))])),
+        hardline,
+        "}"
+      ]);
+    }
+
+    case "FieldDefinition": {
+      return concat([path.call(print, "name"), ": ", path.call(print, "type")]);
+    }
+
     case "FragmentSpread": {
       return concat([
         "...",

tests/graphql_object_type_def/__snapshots__/jsfmt.spec.js.snap

@@ -0,0 +1,14 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`object_type_def.graphql 1`] = `
+type FeedHomeStories {
+  debug_info: String
+  query_title: String
+}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+type FeedHomeStories = {
+  debug_info: String
+  query_title: String
+}
+
+`;

tests/graphql_object_type_def/jsfmt.spec.js

@@ -0,0 +1 @@
+run_spec(__dirname, { parser: "graphql" });

tests/graphql_object_type_def/object_type_def.graphql

@@ -0,0 +1,4 @@
+type FeedHomeStories {
+  debug_info: String
+  query_title: String
+}