Skip PaintPhaseDescendantBlockBackgroundsOnly phase if possible

third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp

Index: third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp b/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
index 89a4faa8c10b8fa062f19ed8359b329f1e7e1c7d..84b8d17f8c95530eb96a21adf94511862f8e8103 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintLayerPainter.cpp
@@ -667,10 +667,11 @@ void PaintLayerPainter::paintForegroundForFragments(const PaintLayerFragments& l
 
     // We have to loop through every fragment multiple times, since we have to issue paint invalidations in each specific phase in order for
     // interleaving of the fragments to work properly.
-    paintForegroundForFragmentsWithPhase(selectionOnly ? PaintPhaseSelection : PaintPhaseDescendantBlockBackgroundsOnly,
-        layerFragments, context, localPaintingInfo, paintFlags, clipState);
-
-    if (!selectionOnly) {
+    if (selectionOnly) {
+        paintForegroundForFragmentsWithPhase(PaintPhaseSelection, layerFragments, context, localPaintingInfo, paintFlags, clipState);
+    } else {
+        if (m_paintLayer.needsPaintPhaseDescendantBlockBackgrounds())
+            paintForegroundForFragmentsWithPhase(PaintPhaseDescendantBlockBackgroundsOnly, layerFragments, context, localPaintingInfo, paintFlags, clipState);
         if (m_paintLayer.needsPaintPhaseFloat())
             paintForegroundForFragmentsWithPhase(PaintPhaseFloat, layerFragments, context, localPaintingInfo, paintFlags, clipState);
         paintForegroundForFragmentsWithPhase(PaintPhaseForeground, layerFragments, context, localPaintingInfo, paintFlags, clipState);