Add VMService GC events

runtime/bin/vmservice/observatory/test/gc_script.dart

+// Copyright (c) 2014, 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.
+
+library gc_script;
+
+import 'dart:async';
+import 'dart:io';
+
+List<int> data;
+
+void grow(int iterations, int size, Duration duration) {
+  if (iterations <= 0) {
+    return;
+  }
+  data = new List<int>(size);
+  new Timer(duration, () => grow(iterations - 1, size, duration));
+}
+
+
+main() {
+  print(''); // Print blank line to signal that we are ready.
+  
+  grow(100, 1 << 24, new Duration(seconds: 1));  
+  
+  // Wait until signaled from spawning test.
+  stdin.first.then((_) => exit(0));
+}