Make Editor::revealSelectionAfterEditingOperation check document availability

third_party/WebKit/Source/core/editing/Editor.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  *
  * 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
@@ skipping 1286 matching lines @@
       false);
   applyParagraphStyleToSelection(
       style, InputEvent::InputType::FormatSetBlockTextDirection);
 }
 
 void Editor::revealSelectionAfterEditingOperation(
     const ScrollAlignment& alignment,
     RevealExtentOption revealExtentOption) {
   if (m_preventRevealSelection)
     return;
+  if (!frame().selection().isAvailable())
+    return;
   frame().selection().revealSelection(alignment, revealExtentOption);
 }
 
 void Editor::transpose() {
   if (!canEdit())
     return;
 
   VisibleSelection selection = frame().selection().selection();
   if (!selection.isCaret())
     return;
@@ skipping 385 matching lines @@
 }
 
 DEFINE_TRACE(Editor) {
   visitor->trace(m_frame);
   visitor->trace(m_lastEditCommand);
   visitor->trace(m_undoStack);
   visitor->trace(m_mark);
 }
 
 }  // namespace blink