RenderView is null for import documents.

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index 365e290fc1a94714532c9ed034b6ea318519f9da..f943e5b6a9a3cd4ab08cee1c700d7d687c9db51e 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -3455,7 +3455,10 @@ void Document::styleResolverChanged(StyleResolverUpdateMode updateMode)
         // We need to manually repaint because we avoid doing all repaints in layout or style
         // recalc while sheets are still loading to avoid FOUC.
         m_pendingSheetLayout = IgnoreLayoutWithPendingSheets;
-        renderView()->repaintViewAndCompositedLayers();
+
+        ASSERT(renderView() || importsController());
+        if (renderView())
+            renderView()->repaintViewAndCompositedLayers();
     }
 }