Have Node::document() return a reference instead of a pointer

Source/core/editing/InsertListCommand.cpp

Index: Source/core/editing/InsertListCommand.cpp
diff --git a/Source/core/editing/InsertListCommand.cpp b/Source/core/editing/InsertListCommand.cpp
index 3645f77cc8d7eedcc4f0f08d89348cc1501f2853..5af5af3f865573ea71cdf038f9481f4aa166ca35 100644
--- a/Source/core/editing/InsertListCommand.cpp
+++ b/Source/core/editing/InsertListCommand.cpp
@@ -378,7 +378,7 @@ PassRefPtr<HTMLElement> InsertListCommand::listifyParagraph(const VisiblePositio
         // Layout is necessary since start's node's inline renderers may have been destroyed by the insertion
         // The end of the content may have changed after the insertion and layout so update it as well.
         if (insertionPos == start.deepEquivalent()) {
-            listElement->document()->updateLayoutIgnorePendingStylesheets();
+            listElement->document().updateLayoutIgnorePendingStylesheets();
             start = startOfParagraph(originalStart, CanSkipOverEditingBoundary);
             end = endOfParagraph(start, CanSkipOverEditingBoundary);
         }