[Isolates] Convert more static data either to read-only or to per-isolate.

src/debug-agent.h

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 90 matching lines @@
   DebuggerAgent* agent_;
   Socket* client_;
 
   DISALLOW_COPY_AND_ASSIGN(DebuggerAgentSession);
 };
 
 
 // Utility methods factored out to be used by the D8 shell as well.
 class DebuggerAgentUtil {
  public:
-  static const char* kContentLength;
-  static int kContentLengthSize;
+  static const char* const kContentLength;
+  static const int kContentLengthSize;
 
   static SmartPointer<char> ReceiveMessage(const Socket* conn);
   static bool SendConnectMessage(const Socket* conn,
                                  const char* embedding_host);
   static bool SendMessage(const Socket* conn, const Vector<uint16_t> message);
   static bool SendMessage(const Socket* conn,
                           const v8::Handle<v8::String> message);
   static int ReceiveAll(const Socket* conn, char* data, int len);
 };
 
 } }  // namespace v8::internal
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 #endif  // V8_DEBUG_AGENT_H_