Add Fasta tests.

pkg/fasta/test/accessors.dart

+// Copyright (c) 2016, 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.
+
+void set onlySetter(value) {
+  print("onlySetter called with $value.");
+}
+
+class C {
+  void set onlySetter(value) {
+    print("C.onlySetter called with $value.");
+  }
+
+  testC() {
+    try {
+      print(onlySetter);
+      throw "No error thrown";
+    } on NoSuchMethodError catch (e) {
+      print("Expected error: $e");
+    }
+    onlySetter = "hest";
+  }
+
+  testD() {
+    print(onlySetter);
+    onlySetter = "hest";
+  }
+}
+
+class D extends C {
+  String get onlySetter() => "D.onlySetter called.";
+
+  void set onlySetter(value) {
+    print("D.onlySetter called with $value.");
+  }
+}
+
+main() {
+  try {
+    print(onlySetter);
+    throw "No error thrown";
+  } on NoSuchMethodError catch (e) {
+    print("Expected error: $e");
+  }
+  onlySetter = "fisk";
+  new C().testC();
+  new D().testD();
+}