When setting needsRepaint, don't stop at non-stacking composited PaintLayers.

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 c55db95b238e21818a63efe71bb5bc54e78b11c0..ebbcff010edb1e67890ee00144b888bcb5bdd24d 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayer.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintLayer.cpp
@@ -918,6 +918,10 @@ LayoutPoint PaintLayer::computeOffsetFromTransformedAncestor() const {
 }
 
 PaintLayer* PaintLayer::compositingContainer() const {
+  // Floats have special paintinng order. Also, the container does not need
+  // to be a stacking context, because floats are not stacked.
+  if (m_layoutObject->isFloating())

[Xianzhu, 2017/01/09 20:04:14]

We can also add "&& !m_layoutObject->parent()->isLayoutBlockFlow() here to
improve performance.

[chrishtr, 2017/01/09 23:28:33]

Done.

+    return m_layoutObject->containingBlock()->enclosingLayer();
   if (!stackingNode()->isStacked())
     return parent();
   if (PaintLayerStackingNode* ancestorStackingNode =