Handle AX help-Text for media time slider.

Source/modules/accessibility/AXNodeObject.cpp

Index: Source/modules/accessibility/AXNodeObject.cpp
diff --git a/Source/modules/accessibility/AXNodeObject.cpp b/Source/modules/accessibility/AXNodeObject.cpp
index 97cbf483acc76bc1c5673ec2c6ae2f4695cbf35f..6e79ce19f6a1582343e14a50267155993d77f1e6 100644
--- a/Source/modules/accessibility/AXNodeObject.cpp
+++ b/Source/modules/accessibility/AXNodeObject.cpp
@@ -38,9 +38,11 @@
 #include "core/html/HTMLInputElement.h"
 #include "core/html/HTMLLabelElement.h"
 #include "core/html/HTMLLegendElement.h"
+#include "core/html/HTMLMediaElement.h"
 #include "core/html/HTMLPlugInElement.h"
 #include "core/html/HTMLSelectElement.h"
 #include "core/html/HTMLTextAreaElement.h"
+#include "core/html/shadow/MediaControlElements.h"
 #include "core/rendering/RenderObject.h"
 #include "modules/accessibility/AXObjectCacheImpl.h"
 #include "platform/UserGestureIndicator.h"
@@ -515,6 +517,15 @@ bool AXNodeObject::isControl() const
         || AXObject::isARIAControl(ariaRoleAttribute()));
 }
 
+bool AXNodeObject::isControllingVideoElement() const
+{
+    Node* node = this->node();
+    if (!node)
+        return true;
+
+    return isHTMLVideoElement(toParentMediaElement(node));
+}
+
 bool AXNodeObject::isEmbeddedObject() const
 {
     return isHTMLPlugInElement(node());