Ensure that executable pages are properly guarded.

src/heap.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 327 matching lines @@
       *target = e.obj_;
       *size = e.size_;
       return;
     }
 
     if (NewSpacePage::IsAtStart(reinterpret_cast<Address>(front_))) {
       NewSpacePage* front_page =
           NewSpacePage::FromAddress(reinterpret_cast<Address>(front_));
       ASSERT(!front_page->prev_page()->is_anchor());
       front_ =
-          reinterpret_cast<intptr_t*>(front_page->prev_page()->body_limit());
+          reinterpret_cast<intptr_t*>(front_page->prev_page()->area_end());
     }
     *target = reinterpret_cast<HeapObject*>(*(--front_));
     *size = static_cast<int>(*(--front_));
     // Assert no underflow.
     SemiSpace::AssertValidRange(reinterpret_cast<Address>(rear_),
                                 reinterpret_cast<Address>(front_));
   }
 
  private:
   // The front of the queue is higher in the memory page chain than the rear.
@@ skipping 118 matching lines @@
   intptr_t CommittedMemory();
 
   // Returns the amount of executable memory currently committed for the heap.
   intptr_t CommittedMemoryExecutable();
 
   // Returns the available bytes in space w/o growing.
   // Heap doesn't guarantee that it can allocate an object that requires
   // all available bytes. Check MaxHeapObjectSize() instead.
   intptr_t Available();
 
-  // Returns the maximum object size in paged space.
-  inline int MaxObjectSizeInPagedSpace();
-
   // Returns of size of all objects residing in the heap.
   intptr_t SizeOfObjects();
 
   // Return the starting address and a mask for the new space.  And-masking an
   // address with the mask will result in the start address of the new space
   // for all addresses in either semispace.
   Address NewSpaceStart() { return new_space_.start(); }
   uintptr_t NewSpaceMask() { return new_space_.mask(); }
   Address NewSpaceTop() { return new_space_.top(); }
 
@@ skipping 2154 matching lines @@
   AssertNoAllocation no_alloc;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG || LIVE_OBJECT_LIST
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_H_