Revert of [heap] Initialize the owner on each page after lospace allocation

src/heap/spaces.h

 // Copyright 2011 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_HEAP_SPACES_H_
 #define V8_HEAP_SPACES_H_
 
 #include <list>
 #include <memory>
 #include <unordered_set>
@@ skipping 299 matching lines @@
     kSweepingPending,
     kSweepingInProgress,
   };
 
   static const intptr_t kAlignment =
       (static_cast<uintptr_t>(1) << kPageSizeBits);
 
   static const intptr_t kAlignmentMask = kAlignment - 1;
 
   static const intptr_t kSizeOffset = 0;
-  static const intptr_t kFlagsOffset = kSizeOffset + kSizetSize;
-  static const intptr_t kAreaStartOffset = kFlagsOffset + kIntptrSize;
-  static const intptr_t kAreaEndOffset = kAreaStartOffset + kPointerSize;
-  static const intptr_t kReservationOffset = kAreaEndOffset + kPointerSize;
-  static const intptr_t kOwnerOffset = kReservationOffset + 2 * kPointerSize;
+
+  static const intptr_t kFlagsOffset = kSizeOffset + kPointerSize;
 
   static const size_t kMinHeaderSize =
       kSizeOffset + kSizetSize  // size_t size
       + kIntptrSize             // Flags flags_
       + kPointerSize            // Address area_start_
       + kPointerSize            // Address area_end_
       + 2 * kPointerSize        // base::VirtualMemory reservation_
       + kPointerSize            // Address owner_
       + kPointerSize            // Heap* heap_
       + kIntSize                // int progress_bar_
@@ skipping 2570 matching lines @@
   PageIterator old_iterator_;
   PageIterator code_iterator_;
   PageIterator map_iterator_;
   LargePageIterator lo_iterator_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_SPACES_H_