Check in codegen test expectations.

test/codegen/expect/language/named_argument_test.js

+dart_library.library('language/named_argument_test', null, /* Imports */[
+  'dart_sdk',
+  'expect'
+], function load__named_argument_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 named_argument_test = Object.create(null);
+  let __ToString = () => (__ToString = dart.constFn(dart.definiteFunctionType(core.String, [], {b: dart.dynamic, a: dart.dynamic})))();
+  let __ToString$ = () => (__ToString$ = dart.constFn(dart.definiteFunctionType(core.String, [], {a: dart.dynamic, b: dart.dynamic})))();
+  let VoidTodynamic = () => (VoidTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [])))();
+  named_argument_test.main = function() {
+    let c1 = dart.fn(opts => {
+      let b = opts && 'b' in opts ? opts.b : null;
+      let a = opts && 'a' in opts ? opts.a : null;
+      return dart.str`a: ${a} b: ${b}`;
+    }, __ToString());
+    let c2 = dart.fn(opts => {
+      let a = opts && 'a' in opts ? opts.a : null;
+      let b = opts && 'b' in opts ? opts.b : null;
+      return dart.str`a: ${a} b: ${b}`;
+    }, __ToString$());
+    expect$.Expect.equals('a: 2 b: 1', dart.dcall(c1, {b: 1, a: 2}));
+    expect$.Expect.equals('a: 1 b: 2', dart.dcall(c1, {a: 1, b: 2}));
+    expect$.Expect.equals('a: 2 b: 1', dart.dcall(c2, {b: 1, a: 2}));
+    expect$.Expect.equals('a: 1 b: 2', dart.dcall(c2, {a: 1, b: 2}));
+  };
+  dart.fn(named_argument_test.main, VoidTodynamic());
+  // Exports:
+  exports.named_argument_test = named_argument_test;
+});