Remove background obscuration checks.

sky/engine/core/rendering/RenderObject.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 1181 matching lines @@
     return selectionColor(CSSPropertyWebkitTextEmphasisColor);
 }
 
 void RenderObject::selectionStartEnd(int& spos, int& epos) const
 {
     view()->selectionStartEnd(spos, epos);
 }
 
 StyleDifference RenderObject::adjustStyleDifference(StyleDifference diff) const
 {
-    // If transform, opacity or zIndex changed, then we need to invalidate paints.
-    // Text nodes share style with their parents but transform/opacity/z-index don't apply to them,
-    if (!isText() &&
-        (diff.transformChanged() || diff.opacityChanged() || diff.zIndexChanged())) {
-        diff.setNeedsPaintInvalidation();
-    }
-
-    // If filter changed and it paints with filters, then we need to invalidate paints.
-    if (diff.filterChanged() && hasLayer()) {
-        diff.setNeedsPaintInvalidation();
-    }
-
     // The answer to layerTypeRequired() for plugins, iframes, and canvas can change without the actual
     // style changing, since it depends on whether we decide to composite these elements. When the
     // layer status of one of these elements changes, we need to force a layout.
     if (!diff.needsFullLayout() && style() && isLayerModelObject()) {
         bool requiresLayer = toRenderLayerModelObject(this)->layerTypeRequired() != NoLayer;
         if (hasLayer() != requiresLayer)
             diff.setNeedsFullLayout();
     }
 
     return diff;
@@ skipping 870 matching lines @@
 {
     if (object1) {
         const blink::RenderObject* root = object1;
         while (root->parent())
             root = root->parent();
         root->showRenderTreeAndMark(object1, "*", object2, "-", 0);
     }
 }
 
 #endif