[heap] Fix live object iterator to skip grey filler objects.

src/heap/mark-compact.cc

 // Copyright 2012 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.
 
 #include "src/heap/mark-compact.h"
 
 #include "src/base/atomicops.h"
 #include "src/base/bits.h"
 #include "src/base/sys-info.h"
 #include "src/code-stubs.h"
@@ skipping 86 matching lines @@
   Heap* heap_;
 };
 
 
 static void VerifyMarking(Heap* heap, Address bottom, Address top) {
   VerifyMarkingVisitor visitor(heap);
   HeapObject* object;
   Address next_object_must_be_here_or_later = bottom;
   for (Address current = bottom; current < top;) {
     object = HeapObject::FromAddress(current);
-    if (MarkCompactCollector::IsMarked(object)) {
+    // One word fillers at the end of a black area can be grey.
+    if (MarkCompactCollector::IsMarked(object) &&
+        object->map() != heap->one_pointer_filler_map()) {
       CHECK(Marking::IsBlack(ObjectMarking::MarkBitFrom(object)));
       CHECK(current >= next_object_must_be_here_or_later);
       object->Iterate(&visitor);
       next_object_must_be_here_or_later = current + object->Size();
       // The object is either part of a black area of black allocation or a
       // regular black object
       Page* page = Page::FromAddress(current);
       CHECK(
           page->markbits()->AllBitsSetInRange(
               page->AddressToMarkbitIndex(current),
@@ skipping 3964 matching lines @@
       // The target is always in old space, we don't have to record the slot in
       // the old-to-new remembered set.
       DCHECK(!heap()->InNewSpace(target));
       RecordRelocSlot(host, &rinfo, target);
     }
   }
 }
 
 }  // namespace internal
 }  // namespace v8