Check in codegen test expectations.

test/codegen/expect/language/issue10721_test.js

+dart_library.library('language/issue10721_test', null, /* Imports */[
+  'dart_sdk',
+  'expect'
+], function load__issue10721_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 issue10721_test = Object.create(null);
+  let VoidTovoid = () => (VoidTovoid = dart.constFn(dart.definiteFunctionType(dart.void, [])))();
+  let dynamicTodynamic = () => (dynamicTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [dart.dynamic])))();
+  let dynamic__ToString = () => (dynamic__ToString = dart.constFn(dart.definiteFunctionType(core.String, [dart.dynamic], {arg2: core.int})))();
+  let VoidToint = () => (VoidToint = dart.constFn(dart.definiteFunctionType(core.int, [])))();
+  let VoidTodynamic = () => (VoidTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [])))();
+  let dynamicToFunction = () => (dynamicToFunction = dart.constFn(dart.definiteFunctionType(core.Function, [dart.dynamic])))();
+  issue10721_test.main = function() {
+    expect$.Expect.equals('', issue10721_test.useParameterInClosure(1));
+    expect$.Expect.equals(43, dart.dcall(issue10721_test.updateParameterInClosure(1)));
+  };
+  dart.fn(issue10721_test.main, VoidTovoid());
+  issue10721_test.useParameterInClosure = function(arg1, opts) {
+    let arg2 = opts && 'arg2' in opts ? opts.arg2 : null;
+    if (core.Map.is(arg1)) {
+      return core.String._check(arg1[dartx.keys][dartx.map](dart.dynamic)(dart.fn(key => arg1[dartx.get](key), dynamicTodynamic()))[dartx.first]);
+    } else {
+      return '';
+    }
+  };
+  dart.fn(issue10721_test.useParameterInClosure, dynamic__ToString());
+  issue10721_test.updateParameterInClosure = function(arg1) {
+    if (core.Map.is(arg1)) {
+      return dart.fn(() => arg1 = 42, VoidToint());
+    } else {
+      return dart.fn(() => arg1 = dart.dsend(arg1, '+', 42), VoidTodynamic());
+    }
+  };
+  dart.fn(issue10721_test.updateParameterInClosure, dynamicToFunction());
+  // Exports:
+  exports.issue10721_test = issue10721_test;
+});