Skip PaintLayer empty paint phases if it previously painted nothing

third_party/WebKit/Source/core/layout/LayoutBox.cpp

Index: third_party/WebKit/Source/core/layout/LayoutBox.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBox.cpp b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
index 71fc4248e32f484e2cc9f956f8fa2c97926aa084..c78b58c3c353149ffd873d2f4e39fc31ceca2619 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBox.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
@@ -1482,15 +1482,15 @@ bool LayoutBox::intersectsVisibleViewport()
 
 PaintInvalidationReason LayoutBox::invalidatePaintIfNeeded(PaintInvalidationState& paintInvalidationState, const LayoutBoxModelObject& paintInvalidationContainer)
 {
-    if (isFloating())
-        paintInvalidationState.enclosingSelfPaintingLayer(*this).setNeedsPaintPhaseFloat();
-
-    if (hasBoxDecorationBackground()
-        // We also paint overflow controls in background phase.
-        || (hasOverflowClip() && getScrollableArea()->hasOverflowControls())) {
-        PaintLayer& layer = paintInvalidationState.enclosingSelfPaintingLayer(*this);
-        if (layer.layoutObject() != this)
-            layer.setNeedsPaintPhaseDescendantBlockBackgrounds();
+    PaintLayer& enclosingSelfPaintingLayer = paintInvalidationState.enclosingSelfPaintingLayer(*this);
+    if (enclosingSelfPaintingLayer.layoutObject() != this) {
+        if (isFloating())
+            enclosingSelfPaintingLayer.setNeedsPaintPhaseFloat();
+
+        if (hasBoxDecorationBackground()
+            // We also paint overflow controls in background phase.
+            || (hasOverflowClip() && getScrollableArea()->hasOverflowControls()))
+            enclosingSelfPaintingLayer.setNeedsPaintPhaseDescendantBlockBackgrounds();
     }
 
     PaintInvalidationReason fullInvalidationReason = fullPaintInvalidationReason();