WIP: Reset paint invalidation at transform boundaries.

third_party/WebKit/Source/core/layout/PaintInvalidationState.h

Index: third_party/WebKit/Source/core/layout/PaintInvalidationState.h
diff --git a/third_party/WebKit/Source/core/layout/PaintInvalidationState.h b/third_party/WebKit/Source/core/layout/PaintInvalidationState.h
index 8ab40a46aab57411b83bfe3a0890be6d378f4e86..32c403cce7aff97c5db5e524060d223af73dc13e 100644
--- a/third_party/WebKit/Source/core/layout/PaintInvalidationState.h
+++ b/third_party/WebKit/Source/core/layout/PaintInvalidationState.h
@@ -64,7 +64,7 @@ public:
     bool forcedSubtreeInvalidationRectUpdateWithinContainerOnly() const { return m_forcedSubtreeInvalidationFlags == InvalidationRectUpdate; }
     void setForceSubtreeInvalidationRectUpdateWithinContainer() { m_forcedSubtreeInvalidationFlags |= InvalidationRectUpdate; }
 
-    const LayoutBoxModelObject& paintInvalidationContainer() const { return *m_paintInvalidationContainer; }
+    const LayoutBoxModelObject& paintInvalidationContainer() const { return *m_realPaintInvalidationContainer; }
 
     // Computes the position of the current object ((0,0) in the space of the object)
     // in the space of paint invalidation backing.
@@ -132,12 +132,16 @@ private:
     // It is the enclosing composited object.
     const LayoutBoxModelObject* m_paintInvalidationContainer;
 
+    const LayoutBoxModelObject* m_realPaintInvalidationContainer;
+
     // The current paint invalidation container for stacked contents (stacking contexts or positioned objects).
     // It is the nearest ancestor composited object which establishes a stacking context.
     // See Source/core/paint/README.md ### PaintInvalidationState for details on how stacked contents'
     // paint invalidation containers differ.
     const LayoutBoxModelObject* m_paintInvalidationContainerForStackedContents;
 
+    const LayoutBoxModelObject* m_realPaintInvalidationContainerForStackedContents;
+
     const LayoutObject& m_containerForAbsolutePosition;
 
     // Transform from the initial viewport coordinate system of an outermost
@@ -149,12 +153,15 @@ private:
 
     PaintLayer& m_paintingLayer;
 
+    const PaintInvalidationState* m_transformParent;
+    const PaintInvalidationState* m_parentPaintInvalidationState;
+
 #if ENABLE(ASSERT)
     bool m_didUpdateForChildren;
 #endif
 
-#if ENABLE(ASSERT) && !defined(NDEBUG)
-// #define CHECK_FAST_PATH_SLOW_PATH_EQUALITY
+#ifndef NDEBUG
+#define CHECK_FAST_PATH_SLOW_PATH_EQUALITY
 #endif
 
 #ifdef CHECK_FAST_PATH_SLOW_PATH_EQUALITY