Check in codegen test expectations.

test/codegen/expect/language/deferred_duplicate_prefix1_test_none_multi.js

+dart_library.library('language/deferred_duplicate_prefix1_test_none_multi', null, /* Imports */[
+  'dart_sdk'
+], function load__deferred_duplicate_prefix1_test_none_multi(exports, dart_sdk) {
+  'use strict';
+  const core = dart_sdk.core;
+  const dart = dart_sdk.dart;
+  const dartx = dart_sdk.dartx;
+  const deferred_duplicate_prefix1_test_none_multi = Object.create(null);
+  const deferred_prefix_constraints_lib2 = Object.create(null);
+  let VoidTovoid = () => (VoidTovoid = dart.constFn(dart.definiteFunctionType(dart.void, [])))();
+  let VoidTodynamic = () => (VoidTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [])))();
+  deferred_duplicate_prefix1_test_none_multi.main = function() {
+  };
+  dart.fn(deferred_duplicate_prefix1_test_none_multi.main, VoidTovoid());
+  deferred_prefix_constraints_lib2.foo = function() {
+    return 24;
+  };
+  dart.fn(deferred_prefix_constraints_lib2.foo, VoidTodynamic());
+  // Exports:
+  exports.deferred_duplicate_prefix1_test_none_multi = deferred_duplicate_prefix1_test_none_multi;
+  exports.deferred_prefix_constraints_lib2 = deferred_prefix_constraints_lib2;
+});