Merge to M51: Accessible name calc should allow aria-labelledby to reference aria-hidden

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

Index: third_party/WebKit/Source/modules/accessibility/AXNodeObject.cpp
diff --git a/third_party/WebKit/Source/modules/accessibility/AXNodeObject.cpp b/third_party/WebKit/Source/modules/accessibility/AXNodeObject.cpp
index 36a4afcaad658dcc33d08361997dda629950d440..a907c9b2cf4142c274a63701f1332326f93b516b 100644
--- a/third_party/WebKit/Source/modules/accessibility/AXNodeObject.cpp
+++ b/third_party/WebKit/Source/modules/accessibility/AXNodeObject.cpp
@@ -1620,8 +1620,12 @@ String AXNodeObject::textFromDescendants(AXObjectSet& visited, bool recursive) c
         children.append(ownedChild);
 
     for (AXObject* child : children) {
-        // Skip hidden children
-        if (child->isInertOrAriaHidden())
+        // Don't recurse into children that are explicitly marked as aria-hidden.
+        // Note that we don't call isInertOrAriaHidden because that would return true
+        // if any ancestor is hidden, but we need to be able to compute the accessible
+        // name of object inside hidden subtrees (for example, if aria-labelledby points
+        // to an object that's hidden).
+        if (equalIgnoringCase(child->getAttribute(aria_hiddenAttr), "true"))
             continue;
 
         // If we're going between two layoutObjects that are in separate LayoutBoxes, add