Revert of Retry "Replace RenderFullScreen with top layer"

Source/core/css/resolver/StyleResolver.cpp

Index: Source/core/css/resolver/StyleResolver.cpp
diff --git a/Source/core/css/resolver/StyleResolver.cpp b/Source/core/css/resolver/StyleResolver.cpp
index f47fd6242b37f8e8d0f7ee6840e6b51746b8256c..9ef098decd20a0d3ba192f02d25b35f67ba5364f 100644
--- a/Source/core/css/resolver/StyleResolver.cpp
+++ b/Source/core/css/resolver/StyleResolver.cpp
@@ -880,9 +880,7 @@
     if (pseudoId == BACKDROP && !parent.isInTopLayer())
         return 0;
 
-    // It's safe to have a backdrop since its renderer is always a child of RenderView.
-    ASSERT(static_cast<RenderObject*>(parentRenderer->view())->canHaveGeneratedChildren());
-    if (pseudoId != BACKDROP && !parentRenderer->canHaveGeneratedChildren())
+    if (!parentRenderer->canHaveGeneratedChildren())
         return 0;
 
     RenderStyle* parentStyle = parentRenderer->style();