Check in codegen test expectations.

test/codegen/expect/language/duplicate_interface_test.js

Index: test/codegen/expect/language/duplicate_interface_test.js
diff --git a/test/codegen/expect/language/duplicate_interface_test.js b/test/codegen/expect/language/duplicate_interface_test.js
new file mode 100644
index 0000000000000000000000000000000000000000..177456f4228a668d1a23b6dddaef2b894252f042
--- /dev/null
+++ b/test/codegen/expect/language/duplicate_interface_test.js
@@ -0,0 +1,26 @@
+dart_library.library('language/duplicate_interface_test', null, /* Imports */[
+  'dart_sdk',
+  'expect'
+], function load__duplicate_interface_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 duplicate_interface_test = Object.create(null);
+  const duplicate_interface_lib = Object.create(null);
+  let VoidTodynamic = () => (VoidTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [])))();
+  duplicate_interface_test.InterfB = class InterfB extends core.Object {};
+  duplicate_interface_test.Foo = class Foo extends core.Object {};
+  duplicate_interface_test.Foo[dart.implements] = () => [duplicate_interface_test.InterfB, duplicate_interface_lib.InterfB];
+  duplicate_interface_test.main = function() {
+    expect$.Expect.isTrue(duplicate_interface_test.InterfB.is(new duplicate_interface_test.Foo()));
+    expect$.Expect.isTrue(duplicate_interface_lib.InterfB.is(new duplicate_interface_test.Foo()));
+  };
+  dart.fn(duplicate_interface_test.main, VoidTodynamic());
+  duplicate_interface_lib.InterfA = class InterfA extends core.Object {};
+  duplicate_interface_lib.InterfB = class InterfB extends core.Object {};
+  // Exports:
+  exports.duplicate_interface_test = duplicate_interface_test;
+  exports.duplicate_interface_lib = duplicate_interface_lib;
+});