Remove arrow function return type check (#18589)

changelog_unreleased/typescript/18589.md

@@ -0,0 +1,39 @@
+#### Fix inconsistent formatting of arrow function (#18589 by @fisker)
+
+<!-- prettier-ignore -->
+```tsx
+// Input
+a.map(() => ({
+  name,
+}));
+a.map(():A => ({
+  name,
+}));
+a.map(():{A} => ({
+  name,
+}));
+
+// Prettier stable
+a.map(() => ({
+  name,
+}));
+a.map(
+  (): A => ({
+    name,
+  }),
+);
+a.map((): { A } => ({
+  name,
+}));
+
+// Prettier main
+a.map(() => ({
+  name,
+}));
+a.map((): A => ({
+  name,
+}));
+a.map((): { A } => ({
+  name,
+}));
+```