[inspector_protocol] remove old style domains support

lib/ErrorSupport_h.template

 // Copyright 2016 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.
 
 #ifndef {{"_".join(config.protocol.namespace)}}_ErrorSupport_h
 #define {{"_".join(config.protocol.namespace)}}_ErrorSupport_h
 
 //#include "Forward.h"
 
 {% for namespace in config.protocol.namespace %}
 namespace {{namespace}} {
 {% endfor %}
 
 class {{config.lib.export_macro}} ErrorSupport {
 public:
     ErrorSupport();
-    ErrorSupport(String* errorString);
     ~ErrorSupport();
 
     void push();
     void setName(const String&);
     void pop();
     void addError(const String&);
     bool hasErrors();
     String errors();
 
 private:
     std::vector<String> m_path;
     std::vector<String> m_errors;
-    String* m_errorString;
 };
 
 {% for namespace in config.protocol.namespace %}
 } // namespace {{namespace}}
 {% endfor %}
 
 #endif // !defined({{"_".join(config.protocol.namespace)}}_ErrorSupport_h)