Check in codegen test expectations.

test/codegen/expect/language/deferred_only_constant_test.js

+dart_library.library('language/deferred_only_constant_test', null, /* Imports */[
+  'dart_sdk',
+  'expect'
+], function load__deferred_only_constant_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 deferred_only_constant_test = Object.create(null);
+  const deferred_only_constant_lib = Object.create(null);
+  let dynamicTodynamic = () => (dynamicTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [dart.dynamic])))();
+  let VoidTovoid = () => (VoidTovoid = dart.constFn(dart.definiteFunctionType(dart.void, [])))();
+  let const$;
+  deferred_only_constant_test.main = function() {
+    loadLibrary().then(dart.dynamic)(dart.fn(_ => {
+      expect$.Expect.equals(deferred_only_constant_lib.constant, const$ || (const$ = dart.constList(["a", "b", "c"], core.String)));
+    }, dynamicTodynamic()));
+  };
+  dart.fn(deferred_only_constant_test.main, VoidTovoid());
+  deferred_only_constant_lib.constant = dart.constList(["a", "b", "c"], core.String);
+  // Exports:
+  exports.deferred_only_constant_test = deferred_only_constant_test;
+  exports.deferred_only_constant_lib = deferred_only_constant_lib;
+});