Fix collapsed-border painting for layered table and cells

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

Index: third_party/WebKit/Source/core/paint/PaintInvalidator.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintInvalidator.cpp b/third_party/WebKit/Source/core/paint/PaintInvalidator.cpp
index 53706edb310dded7ec14855f7707cb77bc7b31b6..d8e6e7f2eced417e7755414247171fb11726c4fa 100644
--- a/third_party/WebKit/Source/core/paint/PaintInvalidator.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintInvalidator.cpp
@@ -214,7 +214,16 @@ void PaintInvalidator::updatePaintingLayer(const LayoutObject& object,
   if (object.isLayoutBlockFlow() && toLayoutBlockFlow(object).containsFloats())
     context.paintingLayer->setNeedsPaintPhaseFloat();
 
-  if (&object == &context.paintingLayer->layoutObject())
+  // Table collapsed borders are painted in PaintPhaseDescendantBlockBackgrounds
+  // on the table's layer.
+  if (object.isTable()) {
+    const LayoutTable& table = toLayoutTable(object);
+    if (table.collapseBorders() && !table.collapsedBorders().isEmpty())
+      context.paintingLayer->setNeedsPaintPhaseDescendantBlockBackgrounds();

[wkorman, 2017/02/27 19:46:23]

LayoutTable::invalidatePaintIfNeeded already does this, is that not called when
spinvalidation is enabled, or does this cover another case?

[Xianzhu, 2017/02/27 20:22:49]

LayoutTable::invalidatePaintIfNeeded(PaintInvalidationState) is the
non-spinvalidation path.

+  }
+
+  // The following flags are for descendants of the layer object only.
+  if (object == context.paintingLayer->layoutObject())

[wkorman, 2017/02/27 19:46:23]

Why change from pointer to operator==? Are there perf ramifications?

[Xianzhu, 2017/02/27 20:22:49]

They are the same in binary code, but omitting '&' shortens the source code and
avoids potential errors of comparing address of pointers (e.g. in case that
'object' is changed to a pointer for some reason).

We use references and pointers to LayoutObjects interchangeably in comparison.
See
https://groups.google.com/a/chromium.org/forum/#!searchin/blink-dev/Why$20we$...
for discussion.

     return;
 
   if (object.styleRef().hasOutline())
@@ -226,12 +235,6 @@ void PaintInvalidator::updatePaintingLayer(const LayoutObject& object,
           toLayoutBox(object).getScrollableArea()->hasOverflowControls())) {
     context.paintingLayer->setNeedsPaintPhaseDescendantBlockBackgrounds();
   }
-
-  if (object.isTable()) {
-    const LayoutTable& table = toLayoutTable(object);
-    if (table.collapseBorders() && !table.collapsedBorders().isEmpty())
-      context.paintingLayer->setNeedsPaintPhaseDescendantBlockBackgrounds();
-  }
 }
 
 namespace {