Added Editor stream and sendObjectToEditor RPC into Service Protocol

runtime/observatory/lib/src/repositories/editor.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
+
+part of repositories;
+
+class EditorRepository extends M.EditorRepository {
+  final String editor;
+
+  EditorRepository(this.editor) {
+    assert(this.editor != null);
+  }
+
+  Future<M.Sentinel> sendObject(M.IsolateRef i, M.ObjectRef object) {
+    final isolate = i as S.Isolate;
+    assert(isolate != null);
+    return isolate.invokeRpc(
+        '_sendObjectToEditor', {'editor': editor, 'objectId': object.id});
+  }
+}