Fix layout of the Space class for members accessed via an offset

Bug: v8:9118
Change-Id: I2271a158226a12f69a7efdfcb6c4faccccf98d15
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1715090
Commit-Queue: Bill Ticehurst <billti@microsoft.com>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62923}

src/heap/spaces.cc

@@ -1532,10 +1532,6 @@ void MemoryChunk::ReleaseYoungGenerationBitmap() {
 // -----------------------------------------------------------------------------
 // PagedSpace implementation
 
-void Space::CheckOffsetsAreConsistent() const {
-  DCHECK_EQ(Space::kIdOffset, OFFSET_OF(Space, id_));
-}
-
 void Space::AddAllocationObserver(AllocationObserver* observer) {
   allocation_observers_.push_back(observer);
   StartNextInlineAllocationStep();

src/heap/spaces.h

@@ -412,11 +412,8 @@ class V8_EXPORT_PRIVATE Space : public Malloced {
     external_backing_store_bytes_[ExternalBackingStoreType::kArrayBuffer] = 0;
     external_backing_store_bytes_[ExternalBackingStoreType::kExternalString] =
         0;
-    CheckOffsetsAreConsistent();
   }
 
-  void CheckOffsetsAreConsistent() const;
-
   static inline void MoveExternalBackingStoreBytes(
       ExternalBackingStoreType type, Space* from, Space* to, size_t amount);
 
@@ -531,8 +528,6 @@ class V8_EXPORT_PRIVATE Space : public Malloced {
   // Tracks off-heap memory used by this space.
   std::atomic<size_t>* external_backing_store_bytes_;
 
-  static const intptr_t kIdOffset = 9 * kSystemPointerSize;
-
   bool allocation_observers_paused_;
   Heap* heap_;
   AllocationSpace id_;