Revert of Reland "Implement FullScreen using top layer."

third_party/WebKit/Source/core/dom/Document.cpp

Index: third_party/WebKit/Source/core/dom/Document.cpp
diff --git a/third_party/WebKit/Source/core/dom/Document.cpp b/third_party/WebKit/Source/core/dom/Document.cpp
index 93c32e8c16a849dad8397c059577c2ca848fd277..6b9c2fdfc199b20a4cb5bdf760b86134d96a2593 100644
--- a/third_party/WebKit/Source/core/dom/Document.cpp
+++ b/third_party/WebKit/Source/core/dom/Document.cpp
@@ -5309,12 +5309,9 @@ void Document::removeFromTopLayer(Element* element)
 
 HTMLDialogElement* Document::activeModalDialog() const
 {
-    for (auto it = m_topLayerElements.rbegin(); it != m_topLayerElements.rend(); ++it) {
-        if (isHTMLDialogElement(*it))
-            return toHTMLDialogElement((*it).get());
-    }
-
-    return nullptr;
+    if (m_topLayerElements.isEmpty())
+        return 0;
+    return toHTMLDialogElement(m_topLayerElements.last().get());
 }
 
 void Document::exitPointerLock()