Report compile-time errors for conflicting overrides as specified by latest

tests/language/field_override4_test.dart

Index: tests/language/field_override4_test.dart
===================================================================
--- tests/language/field_override4_test.dart	(revision 0)
+++ tests/language/field_override4_test.dart	(revision 0)
@@ -0,0 +1,23 @@
+// Copyright (c) 2013, 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 we report a compile-time error when an instance field conflicts
+// with an inherited instance method of the same name.
+
+import "package:expect/expect.dart";
+
+class A {
+  var foo = 42;  /// 00: ok
+  get foo => 42;  /// 01: ok
+  foo() => 42;  /// 02: compile-time error
+  set foo(value) { }  /// 03: ok
+}
+
+class B extends A {
+  var foo = 42;
+}
+
+main() {
+  Expect.equals(42, new B().foo);
+}