Don't call splitTreeToNode() with null Node

Source/core/editing/IndentOutdentCommand.cpp

 /*
  * Copyright (C) 2006, 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 158 matching lines @@
         document().updateLayoutIgnorePendingStylesheets();
         visibleStartOfParagraph = VisiblePosition(visibleStartOfParagraph.deepEquivalent());
         visibleEndOfParagraph = VisiblePosition(visibleEndOfParagraph.deepEquivalent());
         if (visibleStartOfParagraph.isNotNull() && !isStartOfParagraph(visibleStartOfParagraph))
             insertNodeAt(createBreakElement(document()), visibleStartOfParagraph.deepEquivalent());
         if (visibleEndOfParagraph.isNotNull() && !isEndOfParagraph(visibleEndOfParagraph))
             insertNodeAt(createBreakElement(document()), visibleEndOfParagraph.deepEquivalent());
 
         return;
     }
-    Node* enclosingBlockFlow = enclosingBlock(visibleStartOfParagraph.deepEquivalent().deprecatedNode());
     RefPtrWillBeRawPtr<Node> splitBlockquoteNode = enclosingNode;
-    if (enclosingBlockFlow != enclosingNode)
-        splitBlockquoteNode = splitTreeToNode(enclosingBlockFlow, enclosingNode, true);
-    else {
-        // We split the blockquote at where we start outdenting.
-        Node* highestInlineNode = highestEnclosingNodeOfType(visibleStartOfParagraph.deepEquivalent(), isInline, CannotCrossEditingBoundary, enclosingBlockFlow);
-        splitElement(toElement(enclosingNode), (highestInlineNode) ? highestInlineNode : visibleStartOfParagraph.deepEquivalent().deprecatedNode());
+    if (Node* enclosingBlockFlow = enclosingBlock(visibleStartOfParagraph.deepEquivalent().deprecatedNode())) {
+        if (enclosingBlockFlow != enclosingNode) {
+            splitBlockquoteNode = splitTreeToNode(enclosingBlockFlow, enclosingNode, true);
+        } else {
+            // We split the blockquote at where we start outdenting.
+            Node* highestInlineNode = highestEnclosingNodeOfType(visibleStartOfParagraph.deepEquivalent(), isInline, CannotCrossEditingBoundary, enclosingBlockFlow);
+            splitElement(toElement(enclosingNode), (highestInlineNode) ? highestInlineNode : visibleStartOfParagraph.deepEquivalent().deprecatedNode());
+        }
     }
     RefPtrWillBeRawPtr<Node> placeholder = createBreakElement(document());
     insertNodeBefore(placeholder, splitBlockquoteNode);
     moveParagraph(startOfParagraph(visibleStartOfParagraph), endOfParagraph(visibleEndOfParagraph), VisiblePosition(positionBeforeNode(placeholder.get())), true);
 }
 
 // FIXME: We should merge this function with ApplyBlockElementCommand::formatSelection
 void IndentOutdentCommand::outdentRegion(const VisiblePosition& startOfSelection, const VisiblePosition& endOfSelection)
 {
     VisiblePosition endOfCurrentParagraph = endOfParagraph(startOfSelection);
@@ skipping 40 matching lines @@
 
 void IndentOutdentCommand::formatRange(const Position& start, const Position& end, const Position&, RefPtrWillBeRawPtr<Element>& blockquoteForNextIndent)
 {
     if (tryIndentingAsListItem(start, end))
         blockquoteForNextIndent = nullptr;
     else
         indentIntoBlockquote(start, end, blockquoteForNextIndent);
 }
 
 }