Separate repaint and layout requirements of StyleDifference (Step 3)

Source/core/rendering/RenderLayerModelObject.cpp

Index: Source/core/rendering/RenderLayerModelObject.cpp
diff --git a/Source/core/rendering/RenderLayerModelObject.cpp b/Source/core/rendering/RenderLayerModelObject.cpp
index 6d7d3e040979c7e5b480c2fabdf9c081a1ed4f0d..133f117c13d001bd5746e1606a616e338dcd9224 100644
--- a/Source/core/rendering/RenderLayerModelObject.cpp
+++ b/Source/core/rendering/RenderLayerModelObject.cpp
@@ -103,25 +103,10 @@ void RenderLayerModelObject::styleWillChange(StyleDifference diff, const RenderS
             if (oldStyle->hasClip() != newStyle.hasClip()
                 || oldStyle->clip() != newStyle.clip())
                 layer()->clipper().clearClipRectsIncludingDescendants();
-        }
-
-        if (diff.needsFullLayout() || diff.needsSimplifiedLayout()) {
-            // When a layout hint happens, we go ahead and do a repaint of the layer, since the layer could
-            // end up being destroyed.
+        } else if (diff.needsFullLayout() || diff.needsSimplifiedLayout()) {
             if (hasLayer()) {
-                if (oldStyle->hasClip() != newStyle.hasClip()
-                    || oldStyle->clip() != newStyle.clip()) {
-                    // Composited layers don't need to be repainted when a parent's clip changes.
+                if (!layer()->hasCompositedLayerMapping() && oldStyle->position() != newStyle.position())
                     layer()->repainter().repaintIncludingNonCompositingDescendants(containerForRepaint());
-                } else if (!layer()->hasCompositedLayerMapping()) {
-                    if (oldStyle->position() != newStyle.position()
-                        || oldStyle->zIndex() != newStyle.zIndex()
-                        || oldStyle->hasAutoZIndex() != newStyle.hasAutoZIndex()
-                        || oldStyle->opacity() != newStyle.opacity()
-                        || oldStyle->transform() != newStyle.transform()
-                        || oldStyle->filter() != newStyle.filter())

[Julien - ping for review, 2014/04/25 15:43:04]

Could you explain why it is correct to remove these lines?

[Xianzhu, 2014/04/25 17:32:39]

zIndex, hasAutoZIndex, opacity, transform, filter changes will set
contextSensitiveProperties, and RenderObject::adjustStyleDifference() will
convert them into needsRepaintLayer or needsRecompositeLayer according to the
context.

However, previously, the above logic was not possible if the style diff already
needs full layout, so the above code was needed to recover the needsRepaintLayer
requirement. Actually this was duplicate with the code in
RenderObject::adjustStyleDifference().

Now StyleDifference can express needsRepaintLayer and needsLayout at the same
time, so the above code is no longer needed.

This is the case 2 in the CL description.

Position is still specially handled as before.

-                        layer()->repainter().repaintIncludingNonCompositingDescendants(containerForRepaint());
-                }
             } else if (newStyle.hasTransform() || newStyle.opacity() < 1 || newStyle.hasFilter()) {
                 // If we don't have a layer yet, but we are going to get one because of transform or opacity,
                 //  then we need to repaint the old position of the object.