Ensure that executable pages are properly guarded.

src/serialize.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 538 matching lines @@
   static int SpaceOfObject(HeapObject* object);
   // This just returns the space of the object.  It will return LO_SPACE
   // for all large objects since you can't check the type of the object
   // once the map has been used for the serialization address.
   static int SpaceOfAlreadySerializedObject(HeapObject* object);
   int Allocate(int space, int size, bool* new_page_started);
   int EncodeExternalReference(Address addr) {
     return external_reference_encoder_->Encode(addr);
   }
 
+  int SpaceAreaSize(int space);
+
+  Isolate* isolate_;
   // Keep track of the fullness of each space in order to generate
   // relative addresses for back references.  Large objects are
   // just numbered sequentially since relative addresses make no
   // sense in large object space.
   int fullness_[LAST_SPACE + 1];
   SnapshotByteSink* sink_;
   int current_root_index_;
   ExternalReferenceEncoder* external_reference_encoder_;
   static bool serialization_enabled_;
   // Did we already make use of the fact that serialization was not enabled?
@@ skipping 71 matching lines @@
  private:
   virtual bool ShouldBeInThePartialSnapshotCache(HeapObject* o) {
     return false;
   }
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_SERIALIZE_H_