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..b3dfe3e4eeb1ec6c7c4389d0e26be262ae1f6bf9 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayer.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintLayer.cpp
@@ -918,6 +918,8 @@ LayoutPoint PaintLayer::computeOffsetFromTransformedAncestor() const {
 }
 
 PaintLayer* PaintLayer::compositingContainer() const {
+  if (m_layoutObject->isFloating())
+    return m_layoutObject->containingBlock()->enclosingLayer();

[Xianzhu, 2017/01/07 01:04:46]

Please add a comment why we needs this, and why we don't need the
compositingContainer to be a stacking context (I think this is because the
floating layer is not stacked, right?)

[chrishtr, 2017/01/07 01:15:00]

Right. Noted.

   if (!stackingNode()->isStacked())
     return parent();
   if (PaintLayerStackingNode* ancestorStackingNode =