- Add conversion of the iterator from Flow to TS

Summary:
`@iterator` and `@asyncIterator` are valid syntaxes for Flow but not for TS which accepts [Symbol.iterator] and [Symbol.asyncIterator]. According to flow lexer these are the only valid syntaxes in this form so checking for other cases prefixed with `@@` should not be required.

Changelog:
[flow-api-translator] - Added conversion of the iterator from Flow to TS

Differential Revision: D68776171

tools/hermes-parser/js/flow-api-translator/__tests__/flowDefToTSDef/fixtures/class/members/method/iterator/spec.js

@@ -0,0 +1,14 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict-local
+ * @format
+ */
+
+declare class Foo {
+  @@iterator(): Iterator<string>;
+  @@asyncIterator(): AsyncIterator<string>;
+}

tools/hermes-parser/js/flow-api-translator/__tests__/flowDefToTSDef/fixtures/class/members/method/iterator/translate-result.shot

@@ -0,0 +1,19 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`flowDefToTSDef class/members/method/iterator 1`] = `
+"/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ *
+ * @format
+ */
+
+declare class Foo {
+  [Symbol.iterator](): Iterator<string>;
+  [Symbol.asyncIterator](): AsyncIterator<string>;
+}
+"
+`;

tools/hermes-parser/js/flow-api-translator/src/flowDefToTSDef.js

@@ -928,12 +928,25 @@ const getTransforms = (
               cloneJSDocCommentsToNewNode(member, newNode);
               classMembers.push(newNode);
             } else {
+              const key =
+                member.key.type === 'Identifier' &&
+                member.key.name.startsWith('@@') &&
+                // $FlowFixMe[prop-missing]
+                ['iterator', 'asyncIterator'].includes(member.key.name.slice(2))
+                  ? {
+                      type: 'Identifier',
+                      loc: DUMMY_LOC,
+                      // $FlowFixMe[prop-missing]
+                      name: `[Symbol.${member.key.name.slice(2)}]`,
+                    }
+                  : member.key;
+
               const newNode: TSESTree.MethodDefinitionAmbiguous = {
                 type: 'MethodDefinition',
                 loc: DUMMY_LOC,
                 accessibility: member.accessibility,
                 computed: member.computed ?? false,
-                key: member.key,
+                key,
                 kind: member.kind,
                 optional: member.optional,
                 override: false,