Fix a windows build issue

runtime/vm/flags.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 "vm/flags.h"
 
 #include "platform/assert.h"
 #include "vm/json_stream.h"
 #include "vm/os.h"
 
@@ skipping 37 matching lines @@
       case kBoolean: {
         OS::Print("%s: %s (%s)\n",
             name_, *this->bool_ptr_ ? "true" : "false", comment_);
         break;
       }
       case kInteger: {
         OS::Print("%s: %d (%s)\n", name_, *this->int_ptr_, comment_);
         break;
       }
       case kUint64: {
-        OS::Print("%s: %"Pu64" (%s)\n", name_, *this->uint64_ptr_, comment_);
+        OS::Print("%s: %" Pu64 " (%s)\n", name_, *this->uint64_ptr_, comment_);
         break;
       }
       case kString: {
         if (*this->charp_ptr_ != NULL) {
           OS::Print("%s: '%s' (%s)\n", name_, *this->charp_ptr_, comment_);
         } else {
           OS::Print("%s: (null) (%s)\n", name_, comment_);
         }
         break;
       }
@@ skipping 365 matching lines @@
                          (*flag->bool_ptr_ ? "true" : "false"));
       break;
     }
     case Flag::kInteger: {
       jsflag.AddProperty("flagType", "int");
       jsflag.AddPropertyF("valueAsString", "%d", *flag->int_ptr_);
       break;
     }
     case Flag::kUint64: {
       jsflag.AddProperty("flagType", "uint64_t");
-      jsflag.AddPropertyF("valueAsString", "%"Pu64, *flag->uint64_ptr_);
+      jsflag.AddPropertyF("valueAsString", "%" Pu64, *flag->uint64_ptr_);
       break;
     }
     case Flag::kString: {
       jsflag.AddProperty("flagType", "string");
       if (flag->charp_ptr_ != NULL) {
         jsflag.AddPropertyF("valueAsString", "%s", *flag->charp_ptr_);
       } else {
         // valueAsString missing means NULL.
       }
       break;
@@ skipping 24 matching lines @@
     for (intptr_t i = 0; i < num_flags_; ++i) {
       Flag* flag = flags_[i];
       if (flag->changed_) {
         PrintFlagToJSONArray(&jsarr, flag);
       }
     }
   }
 }
 
 }  // namespace dart