Replace slots buffer with remembered set.

src/heap/spaces-inl.h

Index: src/heap/spaces-inl.h
diff --git a/src/heap/spaces-inl.h b/src/heap/spaces-inl.h
index 515a2027693c7d46954733df88e552dd225ef0ea..ccfb24f6e546d56b08e2dc6994190026a156ee89 100644
--- a/src/heap/spaces-inl.h
+++ b/src/heap/spaces-inl.h
@@ -147,6 +147,19 @@ HeapObject* HeapObjectIterator::FromCurrentPage() {
   return NULL;
 }
 
+// -----------------------------------------------------------------------------
+// LargePageIterator
+
+LargePageIterator::LargePageIterator(LargeObjectSpace* space)
+    : next_page_(space->first_page()) {}
+
+LargePage* LargePageIterator::next() {
+  LargePage* result = next_page_;
+  if (next_page_ != nullptr) {
+    next_page_ = next_page_->next_page();
+  }
+  return result;
+}
 
 // -----------------------------------------------------------------------------
 // MemoryAllocator
@@ -308,15 +321,15 @@ Page* Page::FromAnyPointerAddress(Heap* heap, Address addr) {
   return static_cast<Page*>(MemoryChunk::FromAnyPointerAddress(heap, addr));
 }
 
-
-PointerChunkIterator::PointerChunkIterator(Heap* heap)
+MemoryChunkIterator::MemoryChunkIterator(Heap* heap, Mode mode)
     : state_(kOldSpaceState),
+      mode_(mode),
       old_iterator_(heap->old_space()),
+      code_iterator_(heap->code_space()),
       map_iterator_(heap->map_space()),
       lo_iterator_(heap->lo_space()) {}
 
-
-MemoryChunk* PointerChunkIterator::next() {
+MemoryChunk* MemoryChunkIterator::next() {
   switch (state_) {
     case kOldSpaceState: {
       if (old_iterator_.has_next()) {
@@ -326,33 +339,34 @@ MemoryChunk* PointerChunkIterator::next() {
       // Fall through.
     }
     case kMapState: {
-      if (map_iterator_.has_next()) {
+      if (mode_ != ALL_BUT_MAP_SPACE && map_iterator_.has_next()) {
         return map_iterator_.next();
       }
+      state_ = kCodeState;
+      // Fall through.
+    }
+    case kCodeState: {
+      if (mode_ != ALL_BUT_CODE_SPACE && code_iterator_.has_next()) {
+        return code_iterator_.next();
+      }
       state_ = kLargeObjectState;
       // Fall through.
     }
     case kLargeObjectState: {
-      HeapObject* heap_object;
-      do {
-        heap_object = lo_iterator_.Next();
-        if (heap_object == NULL) {
-          state_ = kFinishedState;
-          return NULL;
-        }
-        // Fixed arrays are the only pointer-containing objects in large
-        // object space.
-      } while (!heap_object->IsFixedArray());
-      MemoryChunk* answer = MemoryChunk::FromAddress(heap_object->address());
-      return answer;
+      MemoryChunk* answer = lo_iterator_.next();
+      if (answer != nullptr) {
+        return answer;
+      }
+      state_ = kFinishedState;
+      // Fall through;
     }
     case kFinishedState:
-      return NULL;
+      return nullptr;
     default:
       break;
   }
   UNREACHABLE();
-  return NULL;
+  return nullptr;
 }