Simplify synthetic roots creation in heap snapshot

src/heap-snapshot-generator-inl.h

Index: src/heap-snapshot-generator-inl.h
diff --git a/src/heap-snapshot-generator-inl.h b/src/heap-snapshot-generator-inl.h
index f7d87aa31b263fb7711c60388d7192ac9051ea3f..3f7e6221661a2e4737053277c35e73ecf39350bf 100644
--- a/src/heap-snapshot-generator-inl.h
+++ b/src/heap-snapshot-generator-inl.h
@@ -43,25 +43,6 @@ HeapGraphEdge** HeapEntry::children_arr() {
 }
 
 
-SnapshotObjectId HeapObjectsMap::GetNthGcSubrootId(int delta) {
-  return kGcRootsFirstSubrootId + delta * kObjectIdStep;
-}
-
-
-HeapObject* V8HeapExplorer::GetNthGcSubrootObject(int delta) {
-  return reinterpret_cast<HeapObject*>(
-      reinterpret_cast<char*>(kFirstGcSubrootObject) +
-      delta * HeapObjectsMap::kObjectIdStep);
-}
-
-
-int V8HeapExplorer::GetGcSubrootOrder(HeapObject* subroot) {
-  return static_cast<int>(
-      (reinterpret_cast<char*>(subroot) -
-       reinterpret_cast<char*>(kFirstGcSubrootObject)) /
-      HeapObjectsMap::kObjectIdStep);
-}
-
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_SNAPSHOT_GENERATOR_INL_H_