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

src/debug-agent.cc

 // Copyright 2009 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 188 matching lines @@
   DebuggerAgentUtil::SendMessage(client_, message);
 }
 
 
 void DebuggerAgentSession::Shutdown() {
   // Shutdown the socket to end the blocking receive.
   client_->Shutdown();
 }
 
 
-const char* DebuggerAgentUtil::kContentLength = "Content-Length";
-int DebuggerAgentUtil::kContentLengthSize =
+const char* const DebuggerAgentUtil::kContentLength = "Content-Length";
+const int DebuggerAgentUtil::kContentLengthSize =
     StrLength(kContentLength);
 
 
 SmartPointer<char> DebuggerAgentUtil::ReceiveMessage(const Socket* conn) {
   int received;
 
   // Read header.
   int content_length = 0;
   while (true) {
     const int kHeaderBufferSize = 80;
@@ skipping 198 matching lines @@
       return total_received;
     }
     total_received += received;
   }
   return total_received;
 }
 
 } }  // namespace v8::internal
 
 #endif  // ENABLE_DEBUGGER_SUPPORT