Revert of Revert "Remove early bail-out in VisitWeakList to investiga…

…te chrasher." (patchset #1 id:1 of https://codereview.chromium.org/1080303002/)

Reason for revert:
Still doesn't work

Original issue's description:
> Revert "Remove early bail-out in VisitWeakList to investigate chrasher."
>
> >  BUG=468601
> >  LOG=n
> >
> >  Review URL: https://codereview.chromium.org/1016353002
> >
> >  Cr-Commit-Position: refs/heads/master@{#27317}
>
> R=hpayer@chromium.org
> BUG=v8:3996,chromium:468601
> LOG=n
>
> Committed: https://crrev.com/835eeafe32f442d7b43fe175237de2c70ed7ceef
> Cr-Commit-Position: refs/heads/master@{#27814}

TBR=hpayer@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:3996,chromium:468601

Review URL: https://codereview.chromium.org/1092783002

Cr-Commit-Position: refs/heads/master@{#27902}

src/heap/objects-visiting.cc

@@ -202,7 +202,6 @@ Object* VisitWeakList(Heap* heap, Object* list, WeakObjectRetainer* retainer,
   while (list != undefined) {
     // Check whether to keep the candidate in the list.
     T* candidate = reinterpret_cast<T*>(list);
-    T* original_candidate = candidate;
 
     Object* retained = retainer->RetainAs(list);
     if (retained != NULL) {
@@ -227,18 +226,6 @@ Object* VisitWeakList(Heap* heap, Object* list, WeakObjectRetainer* retainer,
       // tail is a live object, visit it.
       WeakListVisitor<T>::VisitLiveObject(heap, tail, retainer);
 
-      // The list of weak objects is usually order. It starts with objects
-      // recently allocated in the young generation followed by objects
-      // allocated in the old generation. When a migration failure happened,
-      // the list is not ordered until the next GC that has no migration
-      // failure.
-      // For young generation collections we just have to visit until the last
-      // young generation objects.
-      if (stop_after_young && !heap->migration_failure() &&
-          !heap->previous_migration_failure() &&
-          !heap->InNewSpace(original_candidate)) {
-        return head;
-      }
     } else {
       WeakListVisitor<T>::VisitPhantomObject(heap, candidate);
     }