Eliminate need for va_copy in json.cc

runtime/platform/json.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 "platform/json.h"
 
 #include "platform/assert.h"
 #include "platform/globals.h"
 #include "platform/utils.h"
 #include "vm/os.h"
 
 namespace dart {
 
-#ifndef va_copy
-#define va_copy(dst, src) (memmove(&(dst), &(src), sizeof(dst)))
-#endif  /* va_copy */
-
-
 JSONScanner::JSONScanner(const char* json_text) {
   SetText(json_text);
 }
 
 
 void JSONScanner::SetText(const char* json_text) {
   current_pos_ = json_text;
   token_start_ = json_text;
   token_length_ = 0;
   token_ = TokenIllegal;
@@ skipping 318 matching lines @@
   buf_ = NULL;
 }
 
 
 void TextBuffer::Clear() {
   msg_len_ = 0;
   buf_[0] = '\0';
 }
 
 
-intptr_t TextBuffer::Printf(const char* format, va_list args) {
-  va_list args1;
-  va_copy(args1, args);
+intptr_t TextBuffer::Printf(const char* format, ...) {
+  va_list args;
+  va_start(args, format);
   intptr_t remaining = buf_size_ - msg_len_;
   ASSERT(remaining >= 0);
-  intptr_t len = OS::VSNPrint(buf_ + msg_len_, remaining, format, args1);
-  va_end(args1);
+  intptr_t len = OS::VSNPrint(buf_ + msg_len_, remaining, format, args);
+  va_end(args);
   if (len >= remaining) {
     const int kBufferSpareCapacity = 64;  // Somewhat arbitrary.
     GrowBuffer(len + kBufferSpareCapacity);
     remaining = buf_size_ - msg_len_;
     ASSERT(remaining > len);
     va_list args2;
-    va_copy(args2, args);
+    va_start(args2, format);
     intptr_t len2 = OS::VSNPrint(buf_ + msg_len_, remaining, format, args2);
     va_end(args2);
     ASSERT(len == len2);
   }
   msg_len_ += len;
   buf_[msg_len_] = '\0';
   return len;
 }
 
 
-intptr_t TextBuffer::Printf(const char* format, ...) {
-  va_list args;
-  va_start(args, format);
-  intptr_t len = this->Printf(format, args);
-  va_end(args);
-  return len;
-}
-
-
 void TextBuffer::GrowBuffer(intptr_t len) {
   intptr_t new_size = buf_size_ + len;
   char* new_buf = reinterpret_cast<char*>(realloc(buf_, new_size));
   ASSERT(new_buf != NULL);
   buf_ = new_buf;
   buf_size_ = new_size;
 }
 
 }  // namespace dart