Restore sanity to RenderLayerStackingNode::shouldBeNormalFlowOnly

Source/core/rendering/RenderLayerStackingNode.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 165 matching lines @@
 }
 
 void RenderLayerStackingNode::updateNormalFlowList()
 {
     if (!m_normalFlowListDirty)
         return;
 
     ASSERT(m_layerListMutationAllowed);
 
     for (RenderLayer* child = layer()->firstChild(); child; child = child->nextSibling()) {
-        // Ignore non-overflow layers and reflections.
         if (child->stackingNode()->isNormalFlowOnly() && (!layer()->reflectionInfo() || layer()->reflectionInfo()->reflectionLayer() != child)) {
             if (!m_normalFlowList)
                 m_normalFlowList = adoptPtr(new Vector<RenderLayerStackingNode*>);
             m_normalFlowList->append(child->stackingNode());
         }
     }
 
 #if !ASSERT_DISABLED
     updateStackingParentForNormalFlowList(this);
 #endif
 
     m_normalFlowListDirty = false;
 }
 
 void RenderLayerStackingNode::collectLayers(OwnPtr<Vector<RenderLayerStackingNode*> >& posBuffer, OwnPtr<Vector<RenderLayerStackingNode*> >& negBuffer)
 {
     if (layer()->isInTopLayer())
         return;
 
     layer()->updateDescendantDependentFlags();
 
-    // Overflow layers are just painted by their enclosing layers, so they don't get put in zorder lists.
     if (!isNormalFlowOnly()) {
-        // Determine which buffer the child should be in.
         OwnPtr<Vector<RenderLayerStackingNode*> >& buffer = (zIndex() >= 0) ? posBuffer : negBuffer;
-
-        // Create the buffer if it doesn't exist yet.
         if (!buffer)
             buffer = adoptPtr(new Vector<RenderLayerStackingNode*>);
-
-        // Append ourselves at the end of the appropriate buffer.
         buffer->append(this);
     }
 
-    // Recur into our children to collect more layers, but only if we don't establish a stacking context.
     if (!isStackingContext()) {
         for (RenderLayer* child = layer()->firstChild(); child; child = child->nextSibling()) {
-            // Ignore reflections.
             if (!layer()->reflectionInfo() || layer()->reflectionInfo()->reflectionLayer() != child)
                 child->stackingNode()->collectLayers(posBuffer, negBuffer);
         }
     }
 }
 
 #if !ASSERT_DISABLED
 bool RenderLayerStackingNode::isInStackingParentZOrderLists() const
 {
     if (!m_stackingParent || m_stackingParent->zOrderListsDirty())
@@ skipping 61 matching lines @@
         return;
 
     dirtyStackingContextZOrderLists();
 
     if (isStackingContext)
         dirtyZOrderLists();
     else
         clearZOrderLists();
 }
 
+// FIXME: Rename shouldBeNormalFlowOnly to something more accurate now that CSS
+// 2.1 defines the term "normal flow".
 bool RenderLayerStackingNode::shouldBeNormalFlowOnly() const
 {
-    RenderLayerModelObject* renderer = this->renderer();
-
-    const bool couldBeNormalFlow = renderer->hasOverflowClip()
-        || renderer->hasReflection()
-        || renderer->hasMask()
-        || renderer->isCanvas()
-        || renderer->isVideo()
-        || renderer->isEmbeddedObject()
-        || renderer->isRenderIFrame()
-        || (renderer->style()->specifiesColumns() && !layer()->isRootLayer());
-
-    const bool preventsElementFromBeingNormalFlow = renderer->isPositioned()
-        || renderer->hasTransform()
-        || renderer->hasClipPath()
-        || renderer->hasFilter()
-        || renderer->hasBlendMode()
-        || layer()->isTransparent();
-
-    return couldBeNormalFlow && !preventsElementFromBeingNormalFlow;
+    return !isStackingContext() && !renderer()->isPositioned();
 }
 
 void RenderLayerStackingNode::updateIsNormalFlowOnly()
 {
     bool isNormalFlowOnly = shouldBeNormalFlowOnly();
     if (isNormalFlowOnly == this->isNormalFlowOnly())
         return;
 
     m_isNormalFlowOnly = isNormalFlowOnly;
     if (RenderLayer* p = layer()->parent())
@@ skipping 10 matching lines @@
     }
     return 0;
 }
 
 RenderLayerModelObject* RenderLayerStackingNode::renderer() const
 {
     return m_layer->renderer();
 }
 
 } // namespace WebCore