Fix the crash bug about selecting a marquee element.

Source/core/dom/Position.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2009 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 529 matching lines @@
     if (!node || !node->renderer())
         return false;
 
     if (!node->renderer()->isInline())
         return true;
 
     // Don't include inline tables.
     if (node->hasTagName(tableTag))
         return false;
 
+    // A Marquee elements are moving so we should assume their ends are always
+    // visibily distinct.
+    if (node->hasTagName(marqueeTag))
+        return true;
+
     // There is a VisiblePosition inside an empty inline-block container.
     return node->renderer()->isReplaced() && canHaveChildrenForEditing(node) && toRenderBox(node->renderer())->height() != 0 && !node->firstChild();
 }
 
 static Node* enclosingVisualBoundary(Node* node)
 {
     while (node && !endsOfNodeAreVisuallyDistinctPositions(node))
         node = node->parentNode();
 
     return node;
@@ skipping 822 matching lines @@
     pos.showTreeForThis();
 }
 
 void showTree(const WebCore::Position* pos)
 {
     if (pos)
         pos->showTreeForThis();
 }
 
 #endif