Re-enable Object.observe and add enforcement for security invariants.

src/objects.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include "allocation.h"
 #include "assert-scope.h"
 #include "builtins.h"
@@ skipping 2724 matching lines @@
   static const int kElementsOffset = kPropertiesOffset + kPointerSize;
   static const int kHeaderSize = kElementsOffset + kPointerSize;
 
   STATIC_CHECK(kHeaderSize == Internals::kJSObjectHeaderSize);
 
   class BodyDescriptor : public FlexibleBodyDescriptor<kPropertiesOffset> {
    public:
     static inline int SizeOf(Map* map, HeapObject* object);
   };
 
+  Context* GetCreationContext();
+
   // Enqueue change record for Object.observe. May cause GC.
   static void EnqueueChangeRecord(Handle<JSObject> object,
                                   const char* type,
                                   Handle<Name> name,
                                   Handle<Object> old_value);
 
  private:
   friend class DictionaryElementsAccessor;
   friend class JSReceiver;
   friend class Object;
@@ skipping 8415 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_