Check in codegen test expectations.

test/codegen/expect/language/constructor8_test.js

+dart_library.library('language/constructor8_test', null, /* Imports */[
+  'dart_sdk',
+  'expect'
+], function load__constructor8_test(exports, dart_sdk, expect) {
+  'use strict';
+  const core = dart_sdk.core;
+  const dart = dart_sdk.dart;
+  const dartx = dart_sdk.dartx;
+  const expect$ = expect.expect;
+  const constructor8_test = Object.create(null);
+  let VoidToint = () => (VoidToint = dart.constFn(dart.definiteFunctionType(core.int, [])))();
+  let VoidTodynamic = () => (VoidTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [])))();
+  constructor8_test.A = class A extends core.Object {
+    withClosure(a) {
+      this.b = null;
+      let c = null;
+      let f = dart.fn(() => c = 42, VoidToint());
+      this.b = f();
+      expect$.Expect.equals(42, this.b);
+      expect$.Expect.equals(42, c);
+    }
+  };
+  dart.defineNamedConstructor(constructor8_test.A, 'withClosure');
+  dart.setSignature(constructor8_test.A, {
+    constructors: () => ({withClosure: dart.definiteFunctionType(constructor8_test.A, [core.Map])})
+  });
+  constructor8_test.main = function() {
+    new constructor8_test.A.withClosure(null);
+    new constructor8_test.A.withClosure(dart.map());
+  };
+  dart.fn(constructor8_test.main, VoidTodynamic());
+  // Exports:
+  exports.constructor8_test = constructor8_test;
+});