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

runtime/vm/snapshot_test.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 "include/dart_debugger_api.h"
 #include "platform/assert.h"
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_api_message.h"
@@ skipping 31 matching lines @@
       return expected.raw() == actual.raw();
     }
     return false;
   }
   return false;
 }
 
 
 static uint8_t* malloc_allocator(
     uint8_t* ptr, intptr_t old_size, intptr_t new_size) {
-  return reinterpret_cast<uint8_t*>(realloc(ptr, new_size));
+  return Utils::Realloc(ptr, old_size, new_size);
 }
 
 
 static uint8_t* zone_allocator(
     uint8_t* ptr, intptr_t old_size, intptr_t new_size) {
   Zone* zone = Isolate::Current()->current_zone();
   return zone->Realloc<uint8_t>(ptr, old_size, new_size);
 }
 
 
@@ skipping 2425 matching lines @@
   result = Dart_RunLoop();
   EXPECT(Dart_IsError(result));
   EXPECT(Dart_ErrorHasException(result));
   EXPECT_SUBSTRING("Exception: nulltruefalse123456æøå3.14[]100123456789\n",
                    Dart_GetError(result));
 
   Dart_ExitScope();
 }
 
 }  // namespace dart