Move mojo and mojom from mojo/public/dart to mojo/dart/packages

benchmarks/mojo_rtt_benchmark/BUILD.gn

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//mojo/public/dart/rules.gni")
 
 dart_pkg("mojo_rtt_benchmark") {
   apps = [
     [
       "dart_rtt_benchmark",
       "lib/main.dart",
     ],
     [
       "dart_echo_server",
       "lib/echo_server.dart",
     ],
     [
       "dart_isolate_rtt_benchmark",
       "lib/isolate.dart",
     ],
   ]
   sources = [
     "pubspec.yaml",
   ]
   deps = [
     "//examples/echo:bindings",
     "//mojo/common/dart",
+    "//mojo/dart/packages/",
     "//mojo/public/dart",
   ]
 }