fix cpp11 compile errors

runtime/vm/json_stream.cc

 // Copyright (c) 2013, 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/assert.h"
 #include "vm/object.h"
 #include "vm/json_stream.h"
 
 
 namespace dart {
@@ skipping 55 matching lines @@
 
 
 void JSONStream::PrintValueBool(bool b) {
   PrintCommaIfNeeded();
   buffer_->Printf("%s", b ? "true" : "false");
 }
 
 
 void JSONStream::PrintValue(intptr_t i) {
   PrintCommaIfNeeded();
-  buffer_->Printf("%"Pd"", i);
+  buffer_->Printf("%" Pd "", i);
 }
 
 
 void JSONStream::PrintValue(double d) {
   PrintCommaIfNeeded();
   buffer_->Printf("%f", d);
 }
 
 
 void JSONStream::PrintValue(const char* s) {
@@ skipping 114 matching lines @@
   intptr_t length = buffer_->length();
   if (length == 0) {
     return false;
   }
   char ch = buffer[length-1];
   return ch != '[' && ch != '{' && ch != ':' && ch != ',';
 }
 
 }  // namespace dart