Add support for running constructors with new

pkg/kernel/testcases/interpreter/constructor_simple_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 program that creates an object by invoking a constor without
+/// initializers.
+main() {
+  var objA = new A(37, 'test');
+  print(objA.a);
+  print(objA.b);
+}
+
+class A {
+  int a;
+  String b;
+
+  A(int a, String b) {
+    this.a = a;
+    this.b = b;
+  }
+}