[Reland #1] Don't create layout objects for children of display-none iframes.

third_party/WebKit/Source/core/layout/LayoutView.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc.
  *               All rights reserved.
  *
  * 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.
  *
@@ skipping 25 matching lines @@
 #include "core/layout/api/LayoutAPIShim.h"
 #include "core/layout/api/LayoutPartItem.h"
 #include "core/layout/api/LayoutViewItem.h"
 #include "core/layout/compositing/PaintLayerCompositor.h"
 #include "core/page/Page.h"
 #include "core/paint/PaintLayer.h"
 #include "core/paint/ViewPaintInvalidator.h"
 #include "core/paint/ViewPainter.h"
 #include "core/svg/SVGDocumentExtensions.h"
 #include "platform/Histogram.h"
+#include "platform/RuntimeEnabledFeatures.h"
 #include "platform/geometry/FloatQuad.h"
 #include "platform/geometry/TransformState.h"
 #include "platform/graphics/paint/PaintController.h"
 #include "platform/instrumentation/tracing/TraceEvent.h"
 #include "platform/instrumentation/tracing/TracedValue.h"
 #include "public/platform/Platform.h"
 #include "wtf/PtrUtil.h"
 
 namespace blink {
 
@@ skipping 125 matching lines @@
 
 void LayoutView::updateLogicalWidth() {
   setLogicalWidth(LayoutUnit(viewLogicalWidthForBoxSizing()));
 }
 
 bool LayoutView::isChildAllowed(LayoutObject* child,
                                 const ComputedStyle&) const {
   return child->isBox();
 }
 
+bool LayoutView::canHaveChildren() const {
+  FrameOwner* owner = frame()->owner();
+  if (!owner)
+    return true;
+  if (!RuntimeEnabledFeatures::displayNoneIFrameCreatesNoLayoutObjectEnabled())
+    return true;
+  return !owner->isDisplayNone();
+}
+
 void LayoutView::layoutContent() {
   ASSERT(needsLayout());
 
   LayoutBlockFlow::layout();
 
 #if DCHECK_IS_ON()
   checkLayoutState();
 #endif
 }
 
@@ skipping 865 matching lines @@
 bool LayoutView::paintedOutputOfObjectHasNoEffectRegardlessOfSize() const {
   // Frame scroll corner is painted using LayoutView as the display item client.
   if (!RuntimeEnabledFeatures::rootLayerScrollingEnabled() &&
       (frameView()->horizontalScrollbar() || frameView()->verticalScrollbar()))
     return false;
 
   return LayoutBlockFlow::paintedOutputOfObjectHasNoEffectRegardlessOfSize();
 }
 
 }  // namespace blink