Expose internal treegrid role, do some cleanup for table/grid/treegrid handling

third_party/WebKit/Source/modules/accessibility/AXARIAGrid.cpp

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 30 matching lines @@
 AXARIAGrid::~AXARIAGrid() {}
 
 AXARIAGrid* AXARIAGrid::Create(LayoutObject* layout_object,
                                AXObjectCacheImpl& ax_object_cache) {
   return new AXARIAGrid(layout_object, ax_object_cache);
 }
 
 bool AXARIAGrid::AddTableRowChild(AXObject* child,
                                   HeapHashSet<Member<AXObject>>& appended_rows,
                                   unsigned& column_count) {
-  if (!child || !child->IsTableRow() || child->RoleValue() != kRowRole)
+  if (!child || child->RoleValue() != kRowRole)
     return false;
 
-  AXTableRow* row = ToAXTableRow(child);
-  if (appended_rows.Contains(row))
+  if (appended_rows.Contains(child))
     return false;
 
   // store the maximum number of columns
-  unsigned row_cell_count = row->Children().size();
+  const unsigned row_cell_count = child->Children().size();
   if (row_cell_count > column_count)
     column_count = row_cell_count;
 
-  row->SetRowIndex((int)rows_.size());
-  rows_.push_back(row);
+  AXTableRow* row = child->IsTableRow() ? ToAXTableRow(child) : 0;
+  if (row) {
+    row->SetRowIndex((int)rows_.size());
+  }
+  rows_.push_back(child);
 
   // Try adding the row if it's not ignoring accessibility,
   // otherwise add its children (the cells) as the grid's children.
-  if (!row->AccessibilityIsIgnored())
-    children_.push_back(row);
+  if (!child->AccessibilityIsIgnored())
+    children_.push_back(child);
   else
-    children_.AppendVector(row->Children());
+    children_.AppendVector(child->Children());
 
-  appended_rows.insert(row);
+  appended_rows.insert(child);
   return true;
 }
 
 void AXARIAGrid::AddChildren() {
   DCHECK(!IsDetached());
   DCHECK(!have_children_);
 
   if (!IsAXTable()) {
     AXLayoutObject::AddChildren();
     return;
@@ skipping 39 matching lines @@
       children_.push_back(column);
   }
 
   AXObject* header_container_object = HeaderContainer();
   if (header_container_object &&
       !header_container_object->AccessibilityIsIgnored())
     children_.push_back(header_container_object);
 }
 
 }  // namespace blink