Don't compute a composited selection for a detached frame

third_party/WebKit/Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 1605 matching lines @@
     // layout.
     if (!m_nestedLayoutCount) {
         updateWidgetGeometries();
         if (LayoutView* layoutView = this->layoutView())
             layoutView->layer()->setNeedsCompositingInputsUpdate();
     }
 }
 
 bool FrameView::computeCompositedSelection(LocalFrame& frame, CompositedSelection& selection)
 {
-    if (frame.view()->shouldThrottleRendering())
+    if (!frame.view() || frame.view()->shouldThrottleRendering())
         return false;
 
     const VisibleSelection& visibleSelection = frame.selection().selection();
     if (!visibleSelection.isCaretOrRange())
         return false;
 
     // Non-editable caret selections lack any kind of UI affordance, and
     // needn't be tracked by the client.
     if (visibleSelection.isCaret() && !visibleSelection.isContentEditable())
         return false;
@@ skipping 2417 matching lines @@
     return m_hiddenForThrottling && m_crossOriginForThrottling;
 }
 
 LayoutBox& FrameView::boxForScrollControlPaintInvalidation() const
 {
     ASSERT(layoutView());
     return *layoutView();
 }
 
 } // namespace blink