Add support for field initialization in objects

pkg/kernel/testcases/interpreter/object_field_initializers_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.
+
+library object_field_initializers_test;
+
+/// Simple program creating an object with instance field initializers in the
+/// declaration of the class.
+///
+/// The static function `fieldInitializer` is used to ensure the fields are
+/// intialized in the correct order by tracking the  order of side effects.
+void main() {
+  var a1 = new A.withoutArguments();
+  print(a1.foo1);
+  print(a1.foo2);
+  print(a1.foo3);
+  var a2 = new A('bar1', 'bar2');
+  print(a2.foo1);
+  print(a2.foo2);
+  print(a2.foo3);
+
+  var b = new B(fieldInitializer(1, 'bar1'), fieldInitializer(2, 'bar2'));
+  print(b.foo1);
+  print(b.foo2);
+  print(b.foo3);
+  print(b.foo4);
+}
+
+class A {
+  String foo1 = 'foo1';
+  String foo2;
+  String foo3 = 'foo3';
+
+  A.withoutArguments();
+  A(String foo1, String foo2) {
+    this.foo1 = foo1;
+    this.foo2 = foo2;
+  }
+}
+
+class B {
+  String foo1 = fieldInitializer(3, 'foo1');
+  String foo2;
+  String foo3 = fieldInitializer(4, 'foo3');
+  String foo4 = fieldInitializer(5, 'foo4');
+
+  B(String foo1, String foo2) {
+    this.foo1 = foo1;
+    this.foo2 = foo2;
+    this.foo4 = fieldInitializer(6, 'bar4');
+  }
+}
+
+String fieldInitializer(int f, String s) {
+  print('$s: $f');
+  return '$s: $f';
+}