Simplify the paint invalidation bits.

sky/engine/core/rendering/RenderObject.cpp

Index: sky/engine/core/rendering/RenderObject.cpp
diff --git a/sky/engine/core/rendering/RenderObject.cpp b/sky/engine/core/rendering/RenderObject.cpp
index 67626e7434aef20a824d508c279455c47dfe8b03..53dd7c2c0a687a4d1561e88b6efb2cfd8d4ecbab 100644
--- a/sky/engine/core/rendering/RenderObject.cpp
+++ b/sky/engine/core/rendering/RenderObject.cpp
@@ -1199,30 +1199,18 @@ void RenderObject::selectionStartEnd(int& spos, int& epos) const
 
 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 the layer does not paint into its own separate backing or it paints with filters, then we need to invalidate paints.
+    // If filter changed and it paints with filters, then we need to invalidate paints.
     if (diff.filterChanged() && hasLayer()) {
-        diff.setNeedsPaintInvalidationLayer();
+        diff.setNeedsPaintInvalidation();
     }
 
-    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.
@@ -1232,12 +1220,6 @@ StyleDifference RenderObject::adjustStyleDifference(StyleDifference diff) const
             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;
 }