[fuchsia][a11y] Fuchsia hidden nodes are ignored AxNodes.

This change fixes a bug where an invisible AxNode was being remapped to
a hidden Fuchsia node, where an ignored AxNode actually matches the
expected behavior.

Documentation for invisible:
https://chromium.googlesource.com/chromium/src/+/lkgr/docs/accessibility/offscreen.md

Test: AXTreeConverterTest.*
Bug: 1135817,fuchsia:60693
Change-Id: Ice78a489a16d4edd357a9181d7bf3d23a32ffb28
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2454092Reviewed-by: Sharon Yang <yangsharon@chromium.org>
Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Commit-Queue: Lucas Radaelli <lucasradaelli@google.com>
Cr-Commit-Position: refs/heads/master@{#814514}

fuchsia/engine/browser/ax_tree_converter.cc

@@ -116,7 +116,7 @@ fuchsia::accessibility::semantics::States ConvertStates(
   }
 
   // Indicates if the node is hidden.
-  states.set_hidden(node.HasState(ax::mojom::State::kInvisible));
+  states.set_hidden(node.IsIgnored());
 
   // The user entered value of the node, if applicable.
   if (node.HasStringAttribute(ax::mojom::StringAttribute::kValue)) {

fuchsia/engine/browser/ax_tree_converter_unittest.cc

@@ -98,7 +98,7 @@ TEST_F(AXTreeConverterTest, AllFieldsSetAndEqual) {
       std::vector<int32_t>{kChildId1, kChildId2, kChildId3}, relative_bounds,
       kLabel1, kDescription1, ax::mojom::CheckedState::kMixed);
   source_node_data.AddBoolAttribute(ax::mojom::BoolAttribute::kSelected, false);
-  source_node_data.RemoveState(ax::mojom::State::kInvisible);
+  source_node_data.RemoveState(ax::mojom::State::kIgnored);
   auto converted_node = AXNodeDataToSemanticNode(source_node_data);
   EXPECT_EQ(static_cast<uint32_t>(source_node_data.id),
             converted_node.node_id());