Simplify the paint invalidation bits.

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 changed, and the layer does not paint into its own separate backing, then we need to invalidate paints.
-    if (diff.transformChanged()) {
-        // Text nodes share style with their parents but transforms don't apply to them,
-        // hence the !isText() check.
-        if (!isText())
-            diff.setNeedsPaintInvalidationLayer();
+    // 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() &&

[ojan, 2015/01/15 01:56:42]

This is the same as the old code, except I merged the transform/opacity/zindex
cases to avoid needless branching.

+        (diff.transformChanged() || diff.opacityChanged() || diff.zIndexChanged())) {
+        diff.setNeedsPaintInvalidation();
     }
 
-    // If opacity or zIndex changed, and the layer does not paint into its own separate backing, then we need to invalidate paints (also
-    // ignoring text nodes)
-    if (diff.opacityChanged() || diff.zIndexChanged()) {
-        if (!isText())
-            diff.setNeedsPaintInvalidationLayer();
+    // If filter changed and it paints with filters, then we need to invalidate paints.
+    if (diff.filterChanged() && hasLayer()) {
+        diff.setNeedsPaintInvalidation();
     }
 
-    // If filter changed, and the layer does not paint into its own separate backing or it paints with filters, then we need to invalidate paints.
-    if (diff.filterChanged() && hasLayer()) {
-        diff.setNeedsPaintInvalidationLayer();
-    }
-
-    if (diff.textOrColorChanged() && !diff.needsPaintInvalidation()

[ojan, 2015/01/15 01:56:42]

I believe we don't need this anymore. If text or color changes it doesn't affect
whether the background is obscured or not, which is the only thing this bool
affects at the moment.

-        && hasImmediateNonWhitespaceTextChildOrPropertiesDependentOnColor())
-        diff.setNeedsPaintInvalidationObject();
-
     // 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();
     }
 
-    // If we have no layer(), just treat a PaintInvalidationLayer hint as a normal paint invalidation.
-    if (diff.needsPaintInvalidationLayer() && !hasLayer()) {
-        diff.clearNeedsPaintInvalidation();
-        diff.setNeedsPaintInvalidationObject();
-    }
-
     return diff;
 }
 
 inline bool RenderObject::hasImmediateNonWhitespaceTextChildOrPropertiesDependentOnColor() const
 {
     if (style()->hasBorder() || style()->hasOutline())
         return true;
     for (const RenderObject* r = slowFirstChild(); r; r = r->nextSibling()) {
         if (r->isText() && !toRenderText(r)->isAllCollapsibleWhitespace())
             return true;
@@ skipping 869 matching lines @@
 {
     if (object1) {
         const blink::RenderObject* root = object1;
         while (root->parent())
             root = root->parent();
         root->showRenderTreeAndMark(object1, "*", object2, "-", 0);
     }
 }
 
 #endif