Check in codegen test expectations.

test/codegen/expect/language/is_nan_test.js

+dart_library.library('language/is_nan_test', null, /* Imports */[
+  'dart_sdk',
+  'expect'
+], function load__is_nan_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 is_nan_test = Object.create(null);
+  let VoidTovoid = () => (VoidTovoid = dart.constFn(dart.definiteFunctionType(dart.void, [])))();
+  let dynamicTobool = () => (dynamicTobool = dart.constFn(dart.definiteFunctionType(core.bool, [dart.dynamic])))();
+  let VoidTodynamic = () => (VoidTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [])))();
+  let dynamicTodynamic = () => (dynamicTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [dart.dynamic])))();
+  is_nan_test.A = class A extends core.Object {
+    get isNaN() {
+      return false;
+    }
+  };
+  is_nan_test.main = function() {
+    expect$.Expect.isTrue(is_nan_test.foo(core.double.NAN));
+    expect$.Expect.isFalse(is_nan_test.foo(new is_nan_test.A()));
+    expect$.Expect.throws(dart.fn(() => is_nan_test.foo('bar'), VoidTovoid()), dart.fn(e => core.NoSuchMethodError.is(e), dynamicTobool()));
+  };
+  dart.fn(is_nan_test.main, VoidTodynamic());
+  is_nan_test.foo = function(a) {
+    return dart.dload(a, 'isNaN');
+  };
+  dart.fn(is_nan_test.foo, dynamicTodynamic());
+  // Exports:
+  exports.is_nan_test = is_nan_test;
+});