Decouple root visitors from object visitors.

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index d7c01afb2cd603f6992067cbf20ab950c35bc598..ba8a3c3a16a778ecb20323b0ad09fc51994c7b2f 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -10326,8 +10326,7 @@ char* HandleScopeImplementer::RestoreThread(char* storage) {
   return storage + ArchiveSpacePerThread();
 }
 
-
-void HandleScopeImplementer::IterateThis(ObjectVisitor* v) {
+void HandleScopeImplementer::IterateThis(RootVisitor* v) {
 #ifdef DEBUG
   bool found_block_before_deferred = false;
 #endif
@@ -10337,13 +10336,14 @@ void HandleScopeImplementer::IterateThis(ObjectVisitor* v) {
     if (last_handle_before_deferred_block_ != NULL &&
         (last_handle_before_deferred_block_ <= &block[kHandleBlockSize]) &&
         (last_handle_before_deferred_block_ >= block)) {
-      v->VisitPointers(block, last_handle_before_deferred_block_);
+      v->VisitRootPointers(Root::kHandleScope, block,
+                           last_handle_before_deferred_block_);
       DCHECK(!found_block_before_deferred);
 #ifdef DEBUG
       found_block_before_deferred = true;
 #endif
     } else {
-      v->VisitPointers(block, &block[kHandleBlockSize]);
+      v->VisitRootPointers(Root::kHandleScope, block, &block[kHandleBlockSize]);
     }
   }
 
@@ -10352,30 +10352,30 @@ void HandleScopeImplementer::IterateThis(ObjectVisitor* v) {
 
   // Iterate over live handles in the last block (if any).
   if (!blocks()->is_empty()) {
-    v->VisitPointers(blocks()->last(), handle_scope_data_.next);
+    v->VisitRootPointers(Root::kHandleScope, blocks()->last(),
+                         handle_scope_data_.next);
   }
 
   List<Context*>* context_lists[2] = { &saved_contexts_, &entered_contexts_};
   for (unsigned i = 0; i < arraysize(context_lists); i++) {
     if (context_lists[i]->is_empty()) continue;
     Object** start = reinterpret_cast<Object**>(&context_lists[i]->first());
-    v->VisitPointers(start, start + context_lists[i]->length());
+    v->VisitRootPointers(Root::kHandleScope, start,
+                         start + context_lists[i]->length());
   }
   if (microtask_context_) {
-    Object** start = reinterpret_cast<Object**>(&microtask_context_);
-    v->VisitPointers(start, start + 1);
+    v->VisitRootPointer(Root::kHandleScope,
+                        reinterpret_cast<Object**>(&microtask_context_));
   }
 }
 
-
-void HandleScopeImplementer::Iterate(ObjectVisitor* v) {
+void HandleScopeImplementer::Iterate(RootVisitor* v) {
   HandleScopeData* current = isolate_->handle_scope_data();
   handle_scope_data_ = *current;
   IterateThis(v);
 }
 
-
-char* HandleScopeImplementer::Iterate(ObjectVisitor* v, char* storage) {
+char* HandleScopeImplementer::Iterate(RootVisitor* v, char* storage) {
   HandleScopeImplementer* scope_implementer =
       reinterpret_cast<HandleScopeImplementer*>(storage);
   scope_implementer->IterateThis(v);
@@ -10428,17 +10428,17 @@ DeferredHandles::~DeferredHandles() {
   }
 }
 
-
-void DeferredHandles::Iterate(ObjectVisitor* v) {
+void DeferredHandles::Iterate(RootVisitor* v) {
   DCHECK(!blocks_.is_empty());
 
   DCHECK((first_block_limit_ >= blocks_.first()) &&
          (first_block_limit_ <= &(blocks_.first())[kHandleBlockSize]));
 
-  v->VisitPointers(blocks_.first(), first_block_limit_);
+  v->VisitRootPointers(Root::kHandleScope, blocks_.first(), first_block_limit_);
 
   for (int i = 1; i < blocks_.length(); i++) {
-    v->VisitPointers(blocks_[i], &blocks_[i][kHandleBlockSize]);
+    v->VisitRootPointers(Root::kHandleScope, blocks_[i],
+                         &blocks_[i][kHandleBlockSize]);
   }
 }