Use 'new' in all the snapshot reallocation functions instead of realloc.

runtime/vm/dart_api_impl.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 "include/dart_api.h"
 
 #include "platform/assert.h"
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
@@ skipping 1024 matching lines @@
 
 
 DART_EXPORT bool Dart_HasLivePorts() {
   Isolate* isolate = Isolate::Current();
   ASSERT(isolate);
   return isolate->message_handler()->HasLivePorts();
 }
 
 
 static uint8_t* allocator(uint8_t* ptr, intptr_t old_size, intptr_t new_size) {
-  void* new_ptr = realloc(reinterpret_cast<void*>(ptr), new_size);
-  return reinterpret_cast<uint8_t*>(new_ptr);
+  return Utils::Realloc(ptr, old_size, new_size);
 }
 
 
 DART_EXPORT bool Dart_PostIntArray(Dart_Port port_id,
                                    intptr_t len,
                                    intptr_t* data) {
   uint8_t* buffer = NULL;
   ApiMessageWriter writer(&buffer, &allocator);
   writer.WriteMessage(len, data);
 
@@ skipping 3780 matching lines @@
   }
   {
     NoGCScope no_gc;
     RawObject* raw_obj = obj.raw();
     isolate->heap()->SetPeer(raw_obj, peer);
   }
   return Api::Success();
 }
 
 }  // namespace dart