Skip PaintLayer empty paint phases if it previously painted nothing

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

Index: third_party/WebKit/Source/core/paint/PaintLayer.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintLayer.cpp b/third_party/WebKit/Source/core/paint/PaintLayer.cpp
index 6686334a7c06441b6fd3c52af2d7093d652e358b..a85e695699fc149224079257648d1178fb773eeb 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayer.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintLayer.cpp
@@ -98,7 +98,7 @@ static CompositingQueryMode gCompositingQueryMode =
     CompositingQueriesAreOnlyAllowedInCertainDocumentLifecyclePhases;
 
 struct SameSizeAsPaintLayer : DisplayItemClient {
-    int bitFields;
+    uint32_t bitFields1, bitFields2;
     void* pointers[9];
     LayoutUnit layoutUnits[4];
     IntSize size;
@@ -160,8 +160,11 @@ PaintLayer::PaintLayer(LayoutBoxModelObject* layoutObject, PaintLayerType type)
     , m_needsRepaint(false)
     , m_previousPaintResult(PaintLayerPainter::FullyPainted)
     , m_needsPaintPhaseDescendantOutlines(false)
+    , m_previousPaintPhaseDescendantOutlinesWasEmpty(false)
     , m_needsPaintPhaseFloat(false)
+    , m_previousPaintPhaseFloatWasEmpty(false)
     , m_needsPaintPhaseDescendantBlockBackgrounds(false)
+    , m_previousPaintPhaseDescendantBlockBackgroundsWasEmpty(false)
     , m_hasDescendantWithClipPath(false)
     , m_hasNonIsolatedDescendantWithBlendMode(false)
     , m_hasAncestorWithClipPath(false)