Add missing Observatory sources to gypi and re-sort.

runtime/observatory/observatory_sources.gypi

 # Copyright (c) 2015, 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 file contains all dart, css, and html sources for Observatory.
 {
   'sources': [
     'lib/allocation_profile.dart',
     'lib/app.dart',
     'lib/cli.dart',
@@ skipping 152 matching lines @@
     'lib/src/elements/persistent_handles.html',
     'lib/src/elements/ports.dart',
     'lib/src/elements/ports.html',
     'lib/src/elements/sample_buffer_control.dart',
     'lib/src/elements/script_inset.dart',
     'lib/src/elements/script_inset.html',
     'lib/src/elements/script_ref_wrapper.dart',
     'lib/src/elements/script_ref.dart',
     'lib/src/elements/script_view.dart',
     'lib/src/elements/script_view.html',
+    'lib/src/elements/sentinel_value.dart',
     'lib/src/elements/service_ref.dart',
     'lib/src/elements/service_ref.html',
     'lib/src/elements/service_view.dart',
     'lib/src/elements/service_view.html',
     'lib/src/elements/source_link_wrapper.dart',
     'lib/src/elements/source_link.dart',
     'lib/src/elements/shims/binding.dart',
     'lib/src/elements/stack_trace_tree_config.dart',
     'lib/src/elements/timeline_page.dart',
     'lib/src/elements/timeline_page.html',
@@ skipping 11 matching lines @@
     'lib/src/models/objects/class.dart',
     'lib/src/models/objects/code.dart',
     'lib/src/models/objects/context.dart',
     'lib/src/models/objects/error.dart',
     'lib/src/models/objects/event.dart',
     'lib/src/models/objects/extension_data.dart',
     'lib/src/models/objects/field.dart',
     'lib/src/models/objects/flag.dart',
     'lib/src/models/objects/frame.dart',
     'lib/src/models/objects/function.dart',
+    'lib/src/models/objects/guarded.dart',
     'lib/src/models/objects/heap_space.dart',
     'lib/src/models/objects/icdata.dart',
     'lib/src/models/objects/instance.dart',
     'lib/src/models/objects/isolate.dart',
     'lib/src/models/objects/library.dart',
     'lib/src/models/objects/local_var_descriptors.dart',
     'lib/src/models/objects/map_association.dart',
     'lib/src/models/objects/megamorphiccache.dart',
     'lib/src/models/objects/notification.dart',
     'lib/src/models/objects/object.dart',
@@ skipping 10 matching lines @@
     'lib/src/models/objects/vm.dart',
     'lib/src/models/repositories/allocation_profile.dart',
     'lib/src/models/repositories/class.dart',
     'lib/src/models/repositories/event.dart',
     'lib/src/models/repositories/flag.dart',
     'lib/src/models/repositories/instance.dart',
     'lib/src/models/repositories/notification.dart',
     'lib/src/models/repositories/sample_profile.dart',
     'lib/src/models/repositories/script.dart',
     'lib/src/models/repositories/target.dart',
+    'lib/src/repositories/allocation_profile.dart',
     'lib/src/repositories/class.dart',
     'lib/src/repositories/event.dart',
     'lib/src/repositories/flag.dart',
     'lib/src/repositories/instance.dart',
     'lib/src/repositories/notification.dart',
     'lib/src/repositories/sample_profile.dart',
     'lib/src/repositories/script.dart',
     'lib/src/repositories/settings.dart',
     'lib/src/repositories/target.dart',
     'lib/src/service/object.dart',
     'lib/tracer.dart',
     'lib/utils.dart',
     'web/favicon.ico',
     'web/index.html',
     'web/main.dart',
     'web/third_party/trace_viewer_full.html',
     'web/timeline.html',
     'web/timeline.js',
     'web/timeline_message_handler.js',
   ],
 }