Reland "[heap] Rework Worklist base type"

This is a reland of commit a19316d9

- Revert malloc_usable_size() changes temporarily to land them in
  isolation.
- Add cosmetics from https://crrev.com/c/3827876

Original change's description:
> [heap] Rework Worklist base type
>
> Worklist uses a singly-linked list of segments to hold entries.
> Segment size was based on a compile-time constant but already stored
> in the segment itself.
>
> Rework the segments to query `malloc_usable_size()` on allocation and
> adjust the capacity properly. For PartitionAlloc, it turns out that
> there's ~20% more capacity available for the 64-element segments.
>
> This slows down actual allocation of the segments with the upside of
> improving utilization and requiring 20% less segments.
>
> Change-Id: Ib8595c3fb9fb75b02e4022f6c525bb59a2df7ab7
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3826047
> Commit-Queue: Anton Bikineev <bikineev@chromium.org>
> Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
> Reviewed-by: Anton Bikineev <bikineev@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#82432}

Change-Id: Ic8c5257cfe3c347b11eea5c513ca7f62e09f637f
Bug: v8:13193
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3829475Reviewed-by: Anton Bikineev <bikineev@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82493}

src/heap/base/worklist.cc

@@ -4,16 +4,12 @@
 
 #include "src/heap/base/worklist.h"
 
-namespace heap {
-namespace base {
-namespace internal {
+namespace heap::base::internal {
 
 // static
 SegmentBase* SegmentBase::GetSentinelSegmentAddress() {
-static SegmentBase kSentinelSegment(0);
-return &kSentinelSegment;
+  static SegmentBase sentinel_segment(0);
+  return &sentinel_segment;
 }
 
-}  // namespace internal
-}  // namespace base
-}  // namespace heap
+}  // namespace heap::base::internal

src/heap/scavenger.cc

@@ -704,7 +704,7 @@ void Scavenger::Process(JobDelegate* delegate) {
       scavenge_visitor.Visit(object_and_size.first);
       done = false;
       if (delegate && ((++objects % kInterruptThreshold) == 0)) {
-        if (!copied_list_local_.IsEmpty()) {
+        if (!copied_list_local_.IsLocalEmpty()) {
           delegate->NotifyConcurrencyIncrease();
         }
       }

test/cctest/heap/test-concurrent-marking.cc

@@ -20,10 +20,10 @@ namespace heap {
 
 void PublishSegment(MarkingWorklist* worklist, HeapObject object) {
   MarkingWorklist::Local local(worklist);
-  for (size_t i = 0; i <= MarkingWorklist::kSegmentSize; i++) {
+  for (size_t i = 0; i < MarkingWorklist::kMinSegmentSizeForTesting; i++) {
     local.Push(object);
   }
-  CHECK(local.Pop(&object));
+  local.Publish();
 }
 
 TEST(ConcurrentMarking) {