Support non-const instance field initializers.

tests/language/field_initialization_order_test.dart

+// Copyright (c) 2012, 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 field initializers are evaluated in the right order.
+
+int counter = 0;
+
+class Mark {
+  static StringBuffer buffer;
+  Mark(value) {
+    buffer.add('$value.');
+  }
+}
+
+class OneField {
+  var a = new Mark('a');
+
+  OneField();
+
+  OneField.init() : a = new Mark('ai');
+}
+
+class TwoFields {
+  var b = new Mark('b');
+  var a = new Mark('a');
+
+  TwoFields();
+
+  TwoFields.initA() : a = new Mark('ai');
+
+  TwoFields.initB() : b = new Mark('bi');
+
+  TwoFields.initBoth() : a = new Mark('ai'), b = new Mark('bi');
+}
+
+class InheritOneField extends OneField {
+  var b = new Mark('b');
+
+  InheritOneField() : super();
+
+  InheritOneField.init() : b = new Mark('bi'), super();
+
+  InheritOneField.superWithInit() : super.init();
+
+  InheritOneField.initWithSuperInit() : b = new Mark('bi'), super.init();
+
+  InheritOneField.initWithSuperInit2() : super.init(), b = new Mark('bi');
+}
+
+String run(callback) {
+  Mark.buffer = new StringBuffer();
+  callback();
+  return Mark.buffer.toString();
+}
+
+main() {
+  Expect.equals('a.', run(() => new OneField()));
+  Expect.equals('a.ai.', run(() => new OneField.init()));
+
+  Expect.equals('b.a.', run(() => new TwoFields()));
+  Expect.equals('b.a.ai.', run(() => new TwoFields.initA()));
+  Expect.equals('b.a.bi.', run(() => new TwoFields.initB()));
+  Expect.equals('b.a.ai.bi.', run(() => new TwoFields.initBoth()));
+
+  Expect.equals('b.a.', run(() => new InheritOneField()));
+  Expect.equals('b.bi.a.', run(() => new InheritOneField.init()));
+  Expect.equals('b.a.ai.', run(() => new InheritOneField.superWithInit()));
+  Expect.equals('b.bi.a.ai.', run(() => new InheritOneField.initWithSuperInit()));
+  Expect.equals('b.a.ai.bi.', run(() => new InheritOneField.initWithSuperInit2()));
+}