Support abstract getters without parameters.

dart/tests/language/abstract_getter_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 to ensure that an abstract getter is not mistaken for a field.
+
+class Foo {
+  abstract get i;
+}
+
+class Bar {
+}
+
+noMethod(e) => e is NoSuchMethodException;
+
+checkIt(f) {
+  Expect.throws(() { f.i = 'hi'; }, noMethod);
+  Expect.throws(() { print(f.i); }, noMethod);
+  Expect.throws(() { print(f.i()); }, noMethod);
+}
+
+main() {
+  checkIt(new Foo());
+  checkIt(new Bar());
+}