Add observatory_pub_packages snapshot to third_party

observatory_pub_packages/analyzer/src/services/runtime/coverage/coverage_lib.dart

+// 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.
+
+/// This library is injected into the applications under coverage.
+library coverage_lib;
+
+import 'dart:io';
+import 'dart:typed_data';
+
+const PORT = 0; // replaced during rewrite
+final _executedIds = new Uint8List(1024 * 64);
+
+touch(int id) {
+  int listIndex = id ~/ 8;
+  int bitIndex = id % 8;
+  _executedIds[listIndex] |= 1 << bitIndex;
+}
+
+postStatistics() {
+  var httpClient = new HttpClient();
+  return httpClient.post('127.0.0.1', PORT, '/statistics')
+      .then((request) {
+        request.add(_executedIds);
+        return request.close();
+      });
+}