Check in codegen test expectations.

test/codegen/expect/language/prefix21_test.js

+dart_library.library('language/prefix21_test', null, /* Imports */[
+  'dart_sdk',
+  'expect'
+], function load__prefix21_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 prefix21_test = Object.create(null);
+  const prefix21_good_lib = Object.create(null);
+  const prefix21_bad_lib = Object.create(null);
+  let VoidTodynamic = () => (VoidTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [])))();
+  let intToint = () => (intToint = dart.constFn(dart.definiteFunctionType(core.int, [core.int])))();
+  prefix21_test.main = function() {
+    expect$.Expect.equals(dart.dcall(prefix21_good_lib.getValue, 42), 42);
+    expect$.Expect.equals(dart.dcall(prefix21_bad_lib.getValue, 42), 84);
+  };
+  dart.fn(prefix21_test.main, VoidTodynamic());
+  prefix21_good_lib.goodFunction = function(x) {
+    return x;
+  };
+  dart.fn(prefix21_good_lib.goodFunction, intToint());
+  dart.copyProperties(prefix21_good_lib, {
+    get getValue() {
+      return prefix21_good_lib.goodFunction;
+    }
+  });
+  prefix21_bad_lib.badFunction = function(x) {
+    return dart.notNull(x) << 1 >>> 0;
+  };
+  dart.fn(prefix21_bad_lib.badFunction, intToint());
+  dart.copyProperties(prefix21_bad_lib, {
+    get getValue() {
+      return prefix21_bad_lib.badFunction;
+    }
+  });
+  // Exports:
+  exports.prefix21_test = prefix21_test;
+  exports.prefix21_good_lib = prefix21_good_lib;
+  exports.prefix21_bad_lib = prefix21_bad_lib;
+});