Fix various inheritance bugs

tests/language/override_field_test.dart

 // Copyright (c) 2011, 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.
 // Dart test checking that static/instance field shadowing do not conflict.
 
 class A {
-  A() {}  // DartC has no implicit constructors yet.
-
   int instanceFieldInA;
   static int staticFieldInA;
 }
 
 class B extends A {
-  B() : super() {}  // DartC has no implicit constructors yet.
-
-  static int instanceFieldInA; /// 01: compile-time error
-  int staticFieldInA; /// 02: static type warning
-  static int staticFieldInA; /// 03: static type warning
-  int instanceFieldInA; /// 04: compile-time error
+  static int instanceFieldInA;   /// 01: compile-time error
+  int staticFieldInA;            /// 02: static type warning
+  static int staticFieldInA;     /// 03: static type warning
 }
 
 main() {
   var x  = new B();
 }