Check in codegen test expectations.

test/codegen/expect/language/map_literal9_test.js

Index: test/codegen/expect/language/map_literal9_test.js
diff --git a/test/codegen/expect/language/map_literal9_test.js b/test/codegen/expect/language/map_literal9_test.js
new file mode 100644
index 0000000000000000000000000000000000000000..7e8b4984e0cf2a14a65e23e3e844e93656f331f1
--- /dev/null
+++ b/test/codegen/expect/language/map_literal9_test.js
@@ -0,0 +1,29 @@
+dart_library.library('language/map_literal9_test', null, /* Imports */[
+  'dart_sdk',
+  'expect'
+], function load__map_literal9_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 map_literal9_test = Object.create(null);
+  let VoidTovoid = () => (VoidTovoid = dart.constFn(dart.definiteFunctionType(dart.void, [])))();
+  let const$;
+  let const$0;
+  map_literal9_test.main = function() {
+    let m1 = const$ || (const$ = dart.const(dart.map({"[object Object]": 0, "1": 1})));
+    expect$.Expect.isFalse(m1[dartx.containsKey](new core.Object()));
+    expect$.Expect.isNull(m1[dartx.get](new core.Object()));
+    expect$.Expect.isFalse(m1[dartx.containsKey](1));
+    expect$.Expect.isNull(m1[dartx.get](1));
+    let m2 = const$0 || (const$0 = dart.const(dart.map({"[object Object]": 0, "1": 1, __proto__: 2})));
+    expect$.Expect.isFalse(m2[dartx.containsKey](new core.Object()));
+    expect$.Expect.isNull(m2[dartx.get](new core.Object()));
+    expect$.Expect.isFalse(m2[dartx.containsKey](1));
+    expect$.Expect.isNull(m2[dartx.get](1));
+  };
+  dart.fn(map_literal9_test.main, VoidTovoid());
+  // Exports:
+  exports.map_literal9_test = map_literal9_test;
+});