Check in codegen test expectations.

test/codegen/expect/language/method_override2_test_none_multi.js

+dart_library.library('language/method_override2_test_none_multi', null, /* Imports */[
+  'dart_sdk'
+], function load__method_override2_test_none_multi(exports, dart_sdk) {
+  'use strict';
+  const core = dart_sdk.core;
+  const dart = dart_sdk.dart;
+  const dartx = dart_sdk.dartx;
+  const method_override2_test_none_multi = Object.create(null);
+  let VoidToint = () => (VoidToint = dart.constFn(dart.definiteFunctionType(core.int, [])))();
+  method_override2_test_none_multi.I = class I extends core.Object {};
+  method_override2_test_none_multi.J = class J extends method_override2_test_none_multi.I {};
+  method_override2_test_none_multi.K = class K extends method_override2_test_none_multi.J {};
+  method_override2_test_none_multi.C = class C extends core.Object {
+    m(opts) {
+      let a = opts && 'a' in opts ? opts.a : null;
+      let b = opts && 'b' in opts ? opts.b : null;
+      core.print(dart.str`${a} ${b}`);
+    }
+  };
+  method_override2_test_none_multi.C[dart.implements] = () => [method_override2_test_none_multi.I];
+  dart.setSignature(method_override2_test_none_multi.C, {
+    methods: () => ({m: dart.definiteFunctionType(dart.dynamic, [], {a: dart.dynamic, b: dart.dynamic})})
+  });
+  method_override2_test_none_multi.D = class D extends core.Object {
+    m(opts) {
+      let c = opts && 'c' in opts ? opts.c : null;
+      let d = opts && 'd' in opts ? opts.d : null;
+      core.print(dart.str`${c} ${d}`);
+    }
+  };
+  dart.setSignature(method_override2_test_none_multi.D, {
+    methods: () => ({m: dart.definiteFunctionType(dart.dynamic, [], {c: dart.dynamic, d: dart.dynamic})})
+  });
+  method_override2_test_none_multi.main = function() {
+    let c = new method_override2_test_none_multi.C();
+    c.m({a: "hello", b: "world"});
+    let d = new method_override2_test_none_multi.D();
+    d.m({c: "hello", d: "world"});
+    core.print(dart.str`${method_override2_test_none_multi.I.is(c)} ${method_override2_test_none_multi.I.is(d)} ${method_override2_test_none_multi.I.is(d)} ${method_override2_test_none_multi.J.is(d)}`);
+  };
+  dart.fn(method_override2_test_none_multi.main, VoidToint());
+  // Exports:
+  exports.method_override2_test_none_multi = method_override2_test_none_multi;
+});