Check in codegen test expectations.

test/codegen/expect/corelib/iterable_test.js

Index: test/codegen/expect/corelib/iterable_test.js
diff --git a/test/codegen/expect/corelib/iterable_test.js b/test/codegen/expect/corelib/iterable_test.js
new file mode 100644
index 0000000000000000000000000000000000000000..48739a1e0cbaddc99abfdbd95c447a12a1ce4536
--- /dev/null
+++ b/test/codegen/expect/corelib/iterable_test.js
@@ -0,0 +1,34 @@
+dart_library.library('corelib/iterable_test', null, /* Imports */[
+  'dart_sdk',
+  'expect'
+], function load__iterable_test(exports, dart_sdk, expect) {
+  'use strict';
+  const core = dart_sdk.core;
+  const collection = dart_sdk.collection;
+  const dart = dart_sdk.dart;
+  const dartx = dart_sdk.dartx;
+  const expect$ = expect.expect;
+  const iterable_test = Object.create(null);
+  let VoidTodynamic = () => (VoidTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [])))();
+  iterable_test.MyIterable = class MyIterable extends collection.IterableBase {
+    new() {
+      super.new();
+    }
+    get iterator() {
+      return [][dartx.iterator];
+    }
+  };
+  dart.addSimpleTypeTests(iterable_test.MyIterable);
+  dart.setSignature(iterable_test.MyIterable, {});
+  dart.defineExtensionMembers(iterable_test.MyIterable, ['iterator']);
+  iterable_test.main = function() {
+    expect$.Expect.isTrue((() => {
+      let _ = [];
+      _[dartx.addAll](new iterable_test.MyIterable());
+      return _;
+    })()[dartx.isEmpty]);
+  };
+  dart.fn(iterable_test.main, VoidTodynamic());
+  // Exports:
+  exports.iterable_test = iterable_test;
+});