A64: Synchronize with r18444.

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 43002d2d2b170346dd124093783bd65c64682b5a..582de32c2bf12fa6c253f5f64286da3f286bfe4a 100644
--- a/src/heap-snapshot-generator-inl.h
+++ b/src/heap-snapshot-generator-inl.h
@@ -59,7 +59,10 @@ int HeapEntry::set_children_index(int index) {
 
 HeapGraphEdge** HeapEntry::children_arr() {
   ASSERT(children_index_ >= 0);
-  return &snapshot_->children()[children_index_];
+  SLOW_ASSERT(children_index_ < snapshot_->children().length() ||
+      (children_index_ == snapshot_->children().length() &&
+       children_count_ == 0));
+  return &snapshot_->children().first() + children_index_;
 }