Revert of [heap] Take page lock when scavenging old to new references in Scavenger.

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 2351 matching lines @@
 
   {
     TRACE_GC(heap()->tracer(), GCTracer::Scope::MINOR_MC_MARK_ROOTS);
     heap()->IterateRoots(&root_visitor, VISIT_ALL_IN_SCAVENGE);
     ProcessMarkingDeque();
   }
 
   {
     TRACE_GC(heap()->tracer(),
              GCTracer::Scope::MINOR_MC_MARK_OLD_TO_NEW_POINTERS);
-    RememberedSet<OLD_TO_NEW>::Iterate(
-        heap(), NON_SYNCHRONIZED,
-        [this](Address addr) { return CheckAndMarkObject(heap(), addr); });
+    RememberedSet<OLD_TO_NEW>::Iterate(heap(), [this](Address addr) {
+      return CheckAndMarkObject(heap(), addr);
+    });
     RememberedSet<OLD_TO_NEW>::IterateTyped(
-        heap(), NON_SYNCHRONIZED,
-        [this](SlotType type, Address host_addr, Address addr) {
+        heap(), [this](SlotType type, Address host_addr, Address addr) {
           return UpdateTypedSlotHelper::UpdateTypedSlot(
               isolate(), type, addr, [this](Object** addr) {
                 return CheckAndMarkObject(heap(),
                                           reinterpret_cast<Address>(addr));
               });
         });
     ProcessMarkingDeque();
   }
 
   {
@@ skipping 1765 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