Set parent on owned children

Fixes an apparent coding error to now mirror AXNodeObject::AddChildren(),
where the owned children correctly get a parent.

Note: the duplication between the 2 methods is disturbing, and the code
should be refactored to be less repetitive.

Bug: None
Change-Id: Ib6bbc20680cdfb017e417de073640742fa15349c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2092909Reviewed-by: Nektarios Paisios <nektar@chromium.org>
Commit-Queue: Aaron Leventhal <aleventhal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#749379}

third_party/blink/renderer/modules/accessibility/ax_layout_object.cc

@@ -2184,6 +2184,9 @@ void AXLayoutObject::AddChildren() {
   AddValidationMessageChild();
   AddAccessibleNodeChildren();
 
+  for (const auto& owned_child : owned_children)
+    AddChild(owned_child);
+
   for (const auto& child : children_) {
     if (!is_continuation && !child->CachedParentObject()) {
       // Never set continuations as a parent object. The first layout object
@@ -2191,9 +2194,6 @@ void AXLayoutObject::AddChildren() {
       child->SetParent(this);
     }
   }
-
-  for (const auto& owned_child : owned_children)
-    AddChild(owned_child);
 }
 
 bool AXLayoutObject::CanHaveChildren() const {