Check in codegen test expectations.

test/codegen/expect/language/mixin_override_regression_test.js

+dart_library.library('language/mixin_override_regression_test', null, /* Imports */[
+  'dart_sdk',
+  'expect'
+], function load__mixin_override_regression_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 mixin_override_regression_test = Object.create(null);
+  let VoidTodynamic = () => (VoidTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [])))();
+  mixin_override_regression_test.C0 = class C0 extends core.Object {
+    m1() {
+      return 5;
+    }
+    m2() {
+      return this.m1();
+    }
+  };
+  dart.setSignature(mixin_override_regression_test.C0, {
+    methods: () => ({
+      m1: dart.definiteFunctionType(core.int, []),
+      m2: dart.definiteFunctionType(core.int, [])
+    })
+  });
+  mixin_override_regression_test.C1 = class C1 extends dart.mixin(core.Object, mixin_override_regression_test.C0) {};
+  mixin_override_regression_test.D = class D extends core.Object {
+    m1() {
+      return 7;
+    }
+  };
+  dart.setSignature(mixin_override_regression_test.D, {
+    methods: () => ({m1: dart.definiteFunctionType(core.int, [])})
+  });
+  mixin_override_regression_test.E0 = class E0 extends dart.mixin(mixin_override_regression_test.C0, mixin_override_regression_test.D) {};
+  mixin_override_regression_test.E1 = class E1 extends dart.mixin(mixin_override_regression_test.C1, mixin_override_regression_test.D) {};
+  mixin_override_regression_test.main = function() {
+    expect$.Expect.equals(7, new mixin_override_regression_test.E0().m2());
+    expect$.Expect.equals(7, new mixin_override_regression_test.E1().m2());
+  };
+  dart.fn(mixin_override_regression_test.main, VoidTodynamic());
+  // Exports:
+  exports.mixin_override_regression_test = mixin_override_regression_test;
+});