Split implementation of KernelToElementMapImpl

tests/compiler/dart2js/is_function_test.dart

+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// Test that checks that we are not added $isFunction properties on closure
+/// classes.
+
+import 'package:async_helper/async_helper.dart';
+import 'package:compiler/src/commandline_options.dart';
+import 'package:compiler/src/compiler.dart';
+import 'package:compiler/src/js_emitter/model.dart';
+import 'package:expect/expect.dart';
+import 'memory_compiler.dart';
+
+const String SOURCE = '''
+import 'dart:isolate';
+main(arg) {}
+''';
+
+main() {
+  asyncTest(() async {
+    var result = await runCompiler(
+        memorySourceFiles: {'main.dart': SOURCE},
+        options: [Flags.enableCheckedMode]);
+    Expect.isTrue(result.isSuccess);
+    Compiler compiler = result.compiler;
+    Program program = compiler.backend.emitter.emitter.programForTesting;
+    var name = compiler.backend.namer
+        .operatorIs(compiler.frontendStrategy.commonElements.functionClass);
+    for (Fragment fragment in program.fragments) {
+      for (Library library in fragment.libraries) {
+        for (Class cls in library.classes) {
+          if (!cls.element.isClosure) continue;
+          for (StubMethod stub in cls.isChecks) {
+            Expect.notEquals(
+                stub.name.key, name.key, "Unexpected ${name.key} stub on $cls");
+          }
+        }
+      }
+    }
+  });
+}