Tidy up the service protocol. Begin improving the documentation.

runtime/vm/flags.cc

 // Copyright (c) 2012, 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.
 
 #include "vm/flags.h"
 
 #include "platform/assert.h"
 #include "vm/json_stream.h"
 #include "vm/os.h"
 
@@ skipping 445 matching lines @@
     default:
       UNREACHABLE();
       break;
   }
 }
 
 
 void Flags::PrintJSON(JSONStream* js) {
   JSONObject jsobj(js);
   jsobj.AddProperty("type", "FlagList");
-  jsobj.AddProperty("id", "flags");
-
   {
     JSONArray jsarr(&jsobj, "unmodifiedFlags");
     for (intptr_t i = 0; i < num_flags_; ++i) {
       Flag* flag = flags_[i];
       if (!flag->changed_) {
         PrintFlagToJSONArray(&jsarr, flag);
       }
     }
   }
   {
     JSONArray jsarr(&jsobj, "modifiedFlags");
     for (intptr_t i = 0; i < num_flags_; ++i) {
       Flag* flag = flags_[i];
       if (flag->changed_) {
         PrintFlagToJSONArray(&jsarr, flag);
       }
     }
   }
 }
 
 }  // namespace dart