[heap] Remove unused IntrusiveMarking class.

src/heap/spaces.cc

Index: src/heap/spaces.cc
diff --git a/src/heap/spaces.cc b/src/heap/spaces.cc
index ba0ddb6e38f87d1ac4180061fca72865bb6c8719..a1f0997659b8bcd323baa585973ad45e31119465 100644
--- a/src/heap/spaces.cc
+++ b/src/heap/spaces.cc
@@ -3140,14 +3140,14 @@ void Page::Print() {
   PrintF("Page@%p in %s\n", this->address(),
          AllocationSpaceName(this->owner()->identity()));
   printf(" --------------------------------------\n");
-  HeapObjectIterator objects(this, heap()->GcSafeSizeOfOldObjectFunction());
+  HeapObjectIterator objects(this, nullptr);
   unsigned mark_size = 0;
   for (HeapObject* object = objects.Next(); object != NULL;
        object = objects.Next()) {
     bool is_marked = Marking::IsBlackOrGrey(Marking::MarkBitFrom(object));
     PrintF(" %c ", (is_marked ? '!' : ' '));  // Indent a little.
     if (is_marked) {
-      mark_size += heap()->GcSafeSizeOfOldObjectFunction()(object);
+      mark_size += object->Size();
     }
     object->ShortPrint();
     PrintF("\n");