Fix a bunch of implicit casts detected by the Win64 compiler

src/zone-inl.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 82 matching lines @@
   SplayTree<Config, ZoneAllocationPolicy>::ResetRoot();
 }
 
 
 void* ZoneObject::operator new(size_t size, Zone* zone) {
   return zone->New(static_cast<int>(size));
 }
 
 inline void* ZoneAllocationPolicy::New(size_t size) {
   ASSERT(zone_);
-  return zone_->New(size);
+  return zone_->New(static_cast<int>(size));
 }
 
 
 template <typename T>
 void* ZoneList<T>::operator new(size_t size, Zone* zone) {
   return zone->New(static_cast<int>(size));
 }
 
 
 ZoneScope::ZoneScope(Isolate* isolate, ZoneScopeMode mode)
     : isolate_(isolate), mode_(mode) {
   isolate_->zone()->scope_nesting_++;
 }
 
 
 bool ZoneScope::ShouldDeleteOnExit() {
   return isolate_->zone()->scope_nesting_ == 1 && mode_ == DELETE_ON_EXIT;
 }
 
 
 int ZoneScope::nesting() {
   return Isolate::Current()->zone()->scope_nesting_;
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_ZONE_INL_H_