dart2js: Make sure that super classes have their inheritance chain set up correctly.

tests/language/inheritance_chain_test.dart

+// Copyright (c) 2015, 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:expect/expect.dart";
+import "inheritance_chain_lib.dart";
+
+class A extends B {
+  get id => "A";
+  get length => 1;
+}
+
+class C extends  D {
+  get id => "C";
+  get length => 3;
+}
+
+class X extends W {
+  get id => "X";
+  get length => -3;
+}
+
+class Z extends Y {
+  get id => "Z";
+  get length => -1;
+}
+
+main() {
+  var instances = [
+    new A(),
+    new B(),
+    new C(),
+    new D(),
+    new W(),
+    new X(),
+    new Y(),
+    new Z(),
+    [],
+  ];
+
+  var o = instances[0];
+  Expect.equals("A", o.id);
+  Expect.equals(1, o.length);
+  Expect.isTrue(o is A);
+  Expect.isTrue(o is B);
+  Expect.isTrue(o is C);
+  Expect.isTrue(o is D);
+  Expect.isTrue(o is W);
+  Expect.isTrue(o is X);
+  Expect.isTrue(o is Y);
+  Expect.isTrue(o is Z);
+  o = instances[1];
+  Expect.equals("B", o.id);
+  Expect.equals(2, o.length);
+  Expect.isTrue(o is B);
+  Expect.isTrue(o is C);
+  Expect.isTrue(o is D);
+  Expect.isTrue(o is W);
+  Expect.isTrue(o is X);
+  Expect.isTrue(o is Y);
+  Expect.isTrue(o is Z);
+  o = instances[2];
+  Expect.equals("C", o.id);
+  Expect.equals(3, o.length);
+  Expect.isTrue(o is C);
+  Expect.isTrue(o is D);
+  Expect.isTrue(o is W);
+  Expect.isTrue(o is X);
+  Expect.isTrue(o is Y);
+  Expect.isTrue(o is Z);
+  o = instances[3];
+  Expect.equals("D", o.id);
+  Expect.equals(4, o.length);
+  Expect.isTrue(o is D);
+  Expect.isTrue(o is W);
+  Expect.isTrue(o is X);
+  Expect.isTrue(o is Y);
+  Expect.isTrue(o is Z);
+  o = instances[4];
+  Expect.equals("W", o.id);
+  Expect.equals(-4, o.length);
+  Expect.isTrue(o is W);
+  o = instances[5];
+  Expect.equals("X", o.id);
+  Expect.equals(-3, o.length);
+  Expect.isTrue(o is X);
+  Expect.isTrue(o is W);
+  o = instances[6];
+  Expect.equals("Y", o.id);
+  Expect.equals(-2, o.length);
+  Expect.isTrue(o is Y);
+  Expect.isTrue(o is X);
+  Expect.isTrue(o is W);
+  o = instances[7];
+  Expect.equals("Z", o.id);
+  Expect.equals(-1, o.length);
+  Expect.isTrue(o is Z);
+  Expect.isTrue(o is Y);
+  Expect.isTrue(o is X);
+  Expect.isTrue(o is W);
+  o = instances[8];
+  Expect.equals(0, o.length);
+}