Check in codegen test expectations.

test/codegen/expect/language/regress_22719_test.js

Index: test/codegen/expect/language/regress_22719_test.js
diff --git a/test/codegen/expect/language/regress_22719_test.js b/test/codegen/expect/language/regress_22719_test.js
new file mode 100644
index 0000000000000000000000000000000000000000..6f7eb0484cd326c737e47fa569bfe2d5a1998671
--- /dev/null
+++ b/test/codegen/expect/language/regress_22719_test.js
@@ -0,0 +1,44 @@
+dart_library.library('language/regress_22719_test', null, /* Imports */[
+  'dart_sdk',
+  'expect'
+], function load__regress_22719_test(exports, dart_sdk, expect) {
+  'use strict';
+  const core = dart_sdk.core;
+  const collection = dart_sdk.collection;
+  const _interceptors = dart_sdk._interceptors;
+  const dart = dart_sdk.dart;
+  const dartx = dart_sdk.dartx;
+  const expect$ = expect.expect;
+  const regress_22719_test = Object.create(null);
+  let JSArrayOfint = () => (JSArrayOfint = dart.constFn(_interceptors.JSArray$(core.int)))();
+  let VoidTovoid = () => (VoidTovoid = dart.constFn(dart.definiteFunctionType(dart.void, [])))();
+  regress_22719_test.A = class A extends core.Object {};
+  regress_22719_test.B = class B extends dart.mixin(core.Object, collection.IterableMixin$(core.int)) {};
+  regress_22719_test.C = class C extends dart.mixin(regress_22719_test.A, collection.IterableMixin$(core.int)) {
+    new() {
+      this.list = JSArrayOfint().of([1, 2, 3, 4, 5]);
+    }
+    get iterator() {
+      return this.list[dartx.iterator];
+    }
+  };
+  regress_22719_test.C[dart.implements] = () => [regress_22719_test.B];
+  dart.setSignature(regress_22719_test.C, {});
+  dart.defineExtensionMembers(regress_22719_test.C, ['iterator']);
+  regress_22719_test.D = class D extends regress_22719_test.C {
+    new() {
+      super.new();
+    }
+  };
+  regress_22719_test.main = function() {
+    let d = new regress_22719_test.D();
+    let expected = 1;
+    for (let i of d) {
+      expect$.Expect.equals(expected, i);
+      expected = expected + 1;
+    }
+  };
+  dart.fn(regress_22719_test.main, VoidTovoid());
+  // Exports:
+  exports.regress_22719_test = regress_22719_test;
+});