Eliminate RawObject::class_ field entirely.

runtime/vm/verifier.cc

Index: runtime/vm/verifier.cc
diff --git a/runtime/vm/verifier.cc b/runtime/vm/verifier.cc
index abe4723fcdc1f401c15eb1097011ff91cdd45c18..d2c339b19c4988aa251560055354e75a32ab7c89 100644
--- a/runtime/vm/verifier.cc
+++ b/runtime/vm/verifier.cc
@@ -23,12 +23,6 @@ void VerifyPointersVisitor::VisitPointers(RawObject** first, RawObject** last) {
   for (RawObject** current = first; current <= last; current++) {
     RawObject* raw_obj = *current;
     if (raw_obj->IsHeapObject()) {
-      // Skip visits of FreeListElements.
-      if (FreeListElement::IsSpecialClass(raw_obj)) {
-        // Only the class of the free list element should ever be visited.
-        ASSERT(first == last);
-        return;
-      }
       uword obj_addr = RawObject::ToAddr(raw_obj);
       if (!Isolate::Current()->heap()->Contains(obj_addr) &&
           !Dart::vm_isolate()->heap()->Contains(obj_addr)) {