Find the current fullscreen video element rather than the one on top of stack

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 f742e3103e9244c4238a1c2a5efe5eec26869abf..83caa4189e9e3a4cb1fb71d9abf9f5ef3b841f98 100644
--- a/Source/core/rendering/compositing/RenderLayerCompositor.cpp
+++ b/Source/core/rendering/compositing/RenderLayerCompositor.cpp
@@ -165,13 +165,17 @@ bool RenderLayerCompositor::acceleratedCompositingForOverflowScrollEnabled() con
 
 static RenderVideo* findFullscreenVideoRenderer(Document& document)
 {
+    // Recursively find the document that is in fullscreen.
     Element* fullscreenElement = FullscreenElementStack::fullscreenElementFrom(document);
+    Document* contentDocument = &document;
     while (fullscreenElement && fullscreenElement->isFrameOwnerElement()) {
-        Document* contentDocument = toHTMLFrameOwnerElement(fullscreenElement)->contentDocument();
+        contentDocument = toHTMLFrameOwnerElement(fullscreenElement)->contentDocument();
         if (!contentDocument)
             return 0;
         fullscreenElement = FullscreenElementStack::fullscreenElementFrom(*contentDocument);
     }
+    // Get the current fullscreen element from the document.
+    fullscreenElement = FullscreenElementStack::currentFullScreenElementFrom(*contentDocument);
     if (!isHTMLVideoElement(fullscreenElement))
         return 0;
     RenderObject* renderer = fullscreenElement->renderer();