Check in codegen test expectations.

test/codegen/expect/language/hash_code_mangling_test.js

Index: test/codegen/expect/language/hash_code_mangling_test.js
diff --git a/test/codegen/expect/language/hash_code_mangling_test.js b/test/codegen/expect/language/hash_code_mangling_test.js
new file mode 100644
index 0000000000000000000000000000000000000000..fc99372cc36bff61467f9eec530ceabf1372c014
--- /dev/null
+++ b/test/codegen/expect/language/hash_code_mangling_test.js
@@ -0,0 +1,29 @@
+dart_library.library('language/hash_code_mangling_test', null, /* Imports */[
+  'dart_sdk',
+  'expect'
+], function load__hash_code_mangling_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 hash_code_mangling_test = Object.create(null);
+  let VoidTovoid = () => (VoidTovoid = dart.constFn(dart.definiteFunctionType(dart.void, [])))();
+  hash_code_mangling_test.Foo = class Foo extends core.Object {
+    new() {
+      this.$identityHash = null;
+    }
+  };
+  hash_code_mangling_test.main = function() {
+    let foo = new hash_code_mangling_test.Foo();
+    foo.$identityHash = 'fisk';
+    expect$.Expect.isTrue(typeof foo.$identityHash == 'string');
+    let hash = foo.hashCode;
+    expect$.Expect.isTrue(typeof hash == 'number');
+    expect$.Expect.isTrue(typeof foo.$identityHash == 'string');
+    expect$.Expect.equals(hash, foo.hashCode);
+  };
+  dart.fn(hash_code_mangling_test.main, VoidTovoid());
+  // Exports:
+  exports.hash_code_mangling_test = hash_code_mangling_test;
+});