Don't call RenderObject::enclosingLayer on a null pointer

Source/core/frame/FrameView.cpp

Index: Source/core/frame/FrameView.cpp
diff --git a/Source/core/frame/FrameView.cpp b/Source/core/frame/FrameView.cpp
index 3a1ec6409f82112ae332983736e9b0e71a77c387..d82d6620fd2077fd264e500f8576e642c4391937 100644
--- a/Source/core/frame/FrameView.cpp
+++ b/Source/core/frame/FrameView.cpp
@@ -2735,7 +2735,7 @@ void FrameView::paintContents(GraphicsContext* p, const IntRect& rect)
     m_isPainting = true;
 
     // m_nodeToDraw is used to draw only one element (and its descendants)
-    RenderObject* eltRenderer = m_nodeToDraw ? m_nodeToDraw->renderer() : 0;
+    RenderObject* renderer = m_nodeToDraw ? m_nodeToDraw->renderer() : 0;
     RenderLayer* rootLayer = renderView->layer();
 
 #ifndef NDEBUG
@@ -2743,11 +2743,11 @@ void FrameView::paintContents(GraphicsContext* p, const IntRect& rect)
     RenderObject::SetLayoutNeededForbiddenScope forbidSetNeedsLayout(rootLayer->renderer());
 #endif
 
-    RenderObject* enclosingLayerRenderer = eltRenderer->enclosingLayer() ? eltRenderer->enclosingLayer()->renderer() : eltRenderer;
+    RenderObject* enclosingLayerRenderer = renderer ? renderer->enclosingLayer()->renderer() : 0;
     rootLayer->paint(p, rect, m_paintBehavior, enclosingLayerRenderer);
 
     if (rootLayer->containsDirtyOverlayScrollbars())
-        rootLayer->paintOverlayScrollbars(p, rect, m_paintBehavior, eltRenderer);
+        rootLayer->paintOverlayScrollbars(p, rect, m_paintBehavior, renderer);
 
     m_isPainting = false;