Decouple root visitors from object visitors.

src/heap/scavenger.cc

 // Copyright 2015 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/scavenger.h"
 
 #include "src/contexts.h"
 #include "src/heap/heap-inl.h"
 #include "src/heap/incremental-marking.h"
 #include "src/heap/objects-visiting-inl.h"
@@ skipping 442 matching lines @@
           StaticVisitorBase::kVisitThinString,
           &ScavengingVisitor<TRANSFER_MARKS, LOGGING_AND_PROFILING_DISABLED>::
               EvacuateThinStringNoShortcut);
     }
   }
 }
 
 
 Isolate* Scavenger::isolate() { return heap()->isolate(); }
 
+void RootScavengeVisitor::VisitPointer(Object** p) { ScavengePointer(p); }
 
-void ScavengeVisitor::VisitPointer(Object** p) { ScavengePointer(p); }
-
-
-void ScavengeVisitor::VisitPointers(Object** start, Object** end) {
+void RootScavengeVisitor::VisitPointers(Object** start, Object** end) {
   // Copy all HeapObject pointers in [start, end)
   for (Object** p = start; p < end; p++) ScavengePointer(p);
 }
 
+void RootScavengeVisitor::VisitRootPointer(Root root, Object** p) {
+  ScavengePointer(p);
+}
 
-void ScavengeVisitor::ScavengePointer(Object** p) {
+void RootScavengeVisitor::VisitRootPointers(Root root, Object** start,
+                                            Object** end) {
+  // Copy all HeapObject pointers in [start, end)
+  for (Object** p = start; p < end; p++) ScavengePointer(p);
+}
+
+void RootScavengeVisitor::ScavengePointer(Object** p) {
   Object* object = *p;
   if (!heap_->InNewSpace(object)) return;
 
   Scavenger::ScavengeObject(reinterpret_cast<HeapObject**>(p),
                             reinterpret_cast<HeapObject*>(object));
 }
 
 }  // namespace internal
 }  // namespace v8