Fix an issue that subtitle is not shown for native fullscreen video that is inside an iframe

Source/core/rendering/compositing/RenderLayerCompositor.cpp

Index: Source/core/rendering/compositing/RenderLayerCompositor.cpp
diff --git a/Source/core/rendering/compositing/RenderLayerCompositor.cpp b/Source/core/rendering/compositing/RenderLayerCompositor.cpp
index b38df7aca97b83ea9ec5ea1d6f24c0380180028d..328c1c8f75844913de75ab08a69dd7fdab98bdad 100644
--- a/Source/core/rendering/compositing/RenderLayerCompositor.cpp
+++ b/Source/core/rendering/compositing/RenderLayerCompositor.cpp
@@ -314,12 +314,12 @@ void RenderLayerCompositor::updateCompositingRequirementsState()
 
 static RenderVideo* findFullscreenVideoRenderer(Document& document)
 {
-    Element* fullscreenElement = FullscreenElementStack::currentFullScreenElementFrom(document);
+    Element* fullscreenElement = FullscreenElementStack::fullscreenElementFrom(document);
     while (fullscreenElement && fullscreenElement->isFrameOwnerElement()) {
         Document* contentDocument = toHTMLFrameOwnerElement(fullscreenElement)->contentDocument();
         if (!contentDocument)
             return 0;
-        fullscreenElement = FullscreenElementStack::currentFullScreenElementFrom(*contentDocument);
+        fullscreenElement = FullscreenElementStack::fullscreenElementFrom(*contentDocument);
     }
     if (!fullscreenElement || !fullscreenElement->hasTagName(videoTag))
         return 0;