Check in codegen test expectations.

test/codegen/expect/language/const_constructor_mixin3_test_none_multi.js

+dart_library.library('language/const_constructor_mixin3_test_none_multi', null, /* Imports */[
+  'dart_sdk'
+], function load__const_constructor_mixin3_test_none_multi(exports, dart_sdk) {
+  'use strict';
+  const core = dart_sdk.core;
+  const dart = dart_sdk.dart;
+  const dartx = dart_sdk.dartx;
+  const const_constructor_mixin3_test_none_multi = Object.create(null);
+  let VoidTodynamic = () => (VoidTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [])))();
+  const_constructor_mixin3_test_none_multi.Mixin = class Mixin extends core.Object {};
+  const_constructor_mixin3_test_none_multi.A = class A extends core.Object {
+    new() {
+    }
+  };
+  dart.setSignature(const_constructor_mixin3_test_none_multi.A, {
+    constructors: () => ({new: dart.definiteFunctionType(const_constructor_mixin3_test_none_multi.A, [])})
+  });
+  const_constructor_mixin3_test_none_multi.B = class B extends const_constructor_mixin3_test_none_multi.A {
+    new() {
+      super.new();
+    }
+  };
+  dart.setSignature(const_constructor_mixin3_test_none_multi.B, {
+    constructors: () => ({new: dart.definiteFunctionType(const_constructor_mixin3_test_none_multi.B, [])})
+  });
+  let const$;
+  const_constructor_mixin3_test_none_multi.main = function() {
+    let a = const$ || (const$ = dart.const(new const_constructor_mixin3_test_none_multi.B()));
+  };
+  dart.fn(const_constructor_mixin3_test_none_multi.main, VoidTodynamic());
+  // Exports:
+  exports.const_constructor_mixin3_test_none_multi = const_constructor_mixin3_test_none_multi;
+});