Eliminate need for va_copy in json.cc

runtime/bin/dbg_connection.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 "bin/dbg_connection.h"
 #include "bin/dartutils.h"
 #include "bin/socket.h"
 #include "bin/thread.h"
 #include "bin/utils.h"
 
@@ skipping 148 matching lines @@
 }
 
 
 static bool IsValidJSON(const char* msg) {
   dart::JSONReader r(msg);
   return r.EndOfObject() != NULL;
 }
 
 
 void DebuggerConnectionHandler::SendError(int msg_id,
-                                          const char* format, ...) {
+                                          const char* err_msg) {
   dart::TextBuffer msg(64);
-  msg.Printf("{\"id\": %d, \"error\": \"", msg_id);
-  va_list args;
-  va_start(args, format);
-  msg.Printf(format, args);
-  va_end(args);
-  msg.Printf("\"}");
+  msg.Printf("{\"id\": %d, \"error\": \"Error: %s\"}", msg_id, err_msg);
   Socket::Write(debugger_fd_, msg.buf(), msg.length());
   // TODO(hausner): Error checking. Probably just shut down the debugger
   // session if we there is an error while writing.
 }
 
 
 void DebuggerConnectionHandler::HandleResumeCmd(const char* json_msg) {
   int msg_id = msgbuf_->MessageId();
   dart::TextBuffer msg(64);
   msg.Printf("{ \"id\": %d }", msg_id);
@@ skipping 32 matching lines @@
   ASSERT(params != NULL);
   dart::JSONReader pr(params);
   pr.Seek("library");
   ASSERT(pr.Type() == dart::JSONReader::kString);
   char lib_url_chars[128];
   pr.GetValueChars(lib_url_chars, sizeof(lib_url_chars));
   Dart_Handle lib_url = Dart_NewString(lib_url_chars);
   ASSERT_NOT_ERROR(lib_url);
   Dart_Handle urls = Dart_GetScriptURLs(lib_url);
   if (Dart_IsError(urls)) {
-    SendError(msg_id, "Error: '%s'.", Dart_GetError(urls));
+    SendError(msg_id, Dart_GetError(urls));
     return;
   }
   ASSERT(Dart_IsList(urls));
   intptr_t num_urls = 0;
   Dart_ListLength(urls, &num_urls);
   msg.Printf("{ \"id\": %d, ", msg_id);
   msg.Printf("\"result\": { \"urls\": [");
   for (int i = 0; i < num_urls; i++) {
     Dart_Handle script_url = Dart_ListGetAt(urls, i);
     ASSERT(Dart_IsString(script_url));
@@ skipping 168 matching lines @@
 
   handler_started_ = true;
   DebuggerConnectionImpl::StartHandler(port_number);
   Dart_SetBreakpointHandler(BreakpointHandler);
 }
 
 
 DebuggerConnectionHandler::~DebuggerConnectionHandler() {
   CloseDbgConnection();
 }