kernel->ssa: get simple constructors working

tests/compiler/dart2js/kernel/constructors_test.dart

+// Copyright (c) 2016, 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.
+
+import 'package:compiler/src/compiler.dart' show Compiler;
+import 'package:test/test.dart';
+
+import 'helper.dart' show check;
+
+main() {
+  test('simple default constructor', () {
+    String code = '''
+class A {
+}
+
+main() {
+  var a = new A();
+  return a;
+}''';
+    return check(code, checkElement: (Compiler compiler) {

[Siggi Cherem (dart-lang), 2016/11/14 18:22:25]

nit: consider defining a helper function for this either here or in helper.dart.

defaultConstructorOf(String cls) => (compiler) {
  return compiler.mainApp.find(cls).lookupDefaultConstructor();
};

[Harry Terkelsen, 2016/11/14 23:23:40]

Done.

+      ClassElement a = compiler.mainApp.find('A');
+      return a.lookupDefaultConstructor();
+    });
+  });
+
+  test('simple default constructor with field', () {
+    String code = '''
+class A {
+  int x = 1;
+}
+
+main() {
+  var a = new A();
+  return a;
+}''';
+    return check(code, checkElement: (Compiler compiler) {
+      ClassElement a = compiler.mainApp.find('A');
+      return a.lookupDefaultConstructor();
+    });
+  });
+}