[cleanup] Remove WeakArrayList::synchronized_capacity

It was never stored with a release store, so can we use the loads as
non-atomic ones.

Bug: v8:7790
Change-Id: Iaf91c0c431d557d74f80f243a0dbdaf9adc5e622
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2880540
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74471}

src/objects/fixed-array-inl.h

@@ -48,8 +48,6 @@ SYNCHRONIZED_SMI_ACCESSORS(FixedArrayBase, length, kLengthOffset)
 
 SYNCHRONIZED_SMI_ACCESSORS(WeakFixedArray, length, kLengthOffset)
 
-SYNCHRONIZED_SMI_ACCESSORS(WeakArrayList, capacity, kCapacityOffset)
-
 Object FixedArrayBase::unchecked_synchronized_length() const {
   return ACQUIRE_READ_FIELD(*this, kLengthOffset);
 }
@@ -248,9 +246,7 @@ inline int FixedArray::AllocatedSize() {
 inline int WeakFixedArray::AllocatedSize() {
   return SizeFor(synchronized_length());
 }
-inline int WeakArrayList::AllocatedSize() {
-  return SizeFor(synchronized_capacity());
-}
+inline int WeakArrayList::AllocatedSize() { return SizeFor(capacity()); }
 
 // Perform a binary search in a fixed array.
 template <SearchMode search_mode, typename T>

src/objects/fixed-array.h

@@ -376,9 +376,6 @@ class WeakArrayList
 
   V8_EXPORT_PRIVATE bool IsFull();
 
-  // Get and set the capacity using acquire loads and release stores.
-  DECL_SYNCHRONIZED_INT_ACCESSORS(capacity)
-
   int AllocatedSize();
 
   class BodyDescriptor;

src/objects/objects.cc

@@ -2313,7 +2313,7 @@ int HeapObject::SizeFromMap(Map map) const {
   }
   if (instance_type == WEAK_ARRAY_LIST_TYPE) {
     return WeakArrayList::SizeForCapacity(
-        WeakArrayList::unchecked_cast(*this).synchronized_capacity());
+        WeakArrayList::unchecked_cast(*this).capacity());
   }
   if (instance_type == SMALL_ORDERED_HASH_SET_TYPE) {
     return SmallOrderedHashSet::SizeFor(