Check in codegen test expectations.

test/codegen/expect/language/async_backwards_compatibility_2_test.js

+dart_library.library('language/async_backwards_compatibility_2_test', null, /* Imports */[
+  'dart_sdk'
+], function load__async_backwards_compatibility_2_test(exports, dart_sdk) {
+  'use strict';
+  const core = dart_sdk.core;
+  const dart = dart_sdk.dart;
+  const dartx = dart_sdk.dartx;
+  const async_backwards_compatibility_2_test = Object.create(null);
+  let VoidTodynamic = () => (VoidTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [])))();
+  dart.copyProperties(async_backwards_compatibility_2_test, {
+    get async() {
+      return 1;
+    }
+  });
+  async_backwards_compatibility_2_test.A = class A extends core.Object {
+    async() {
+      return null;
+    }
+  };
+  dart.setSignature(async_backwards_compatibility_2_test.A, {
+    methods: () => ({async: dart.definiteFunctionType(dart.dynamic, [])})
+  });
+  async_backwards_compatibility_2_test.main = function() {
+    let a = async_backwards_compatibility_2_test.async;
+    let b = new async_backwards_compatibility_2_test.A();
+    let c = b.async();
+  };
+  dart.fn(async_backwards_compatibility_2_test.main, VoidTodynamic());
+  // Exports:
+  exports.async_backwards_compatibility_2_test = async_backwards_compatibility_2_test;
+});