Make sure pages that are closing but not yet closed are still suspended.

third_party/WebKit/Source/core/page/FrameTree.cpp

 /*
  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
  * Copyright (C) 2006 Apple Computer, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 411 matching lines @@
 
   for (Frame* frame = page->mainFrame(); frame;
        frame = frame->tree().traverseNext()) {
     if (frame->tree().name() == name)
       return frame;
   }
 
   // Search the entire tree of each of the other pages in this namespace.
   // FIXME: Is random order OK?
   for (const Page* otherPage : Page::ordinaryPages()) {
-    if (otherPage == page)
+    if (otherPage == page || otherPage->isClosing())
       continue;
     for (Frame* frame = otherPage->mainFrame(); frame;
          frame = frame->tree().traverseNext()) {
       if (frame->tree().name() == name)
         return frame;
     }
   }
 
   return nullptr;
 }
@@ skipping 93 matching lines @@
 void showFrameTree(const blink::Frame* frame) {
   if (!frame) {
     printf("Null input frame\n");
     return;
   }
 
   printFrames(frame->tree().top(), frame, 0);
 }
 
 #endif