*** NOT FOR LANDING *** Paint investigations for bug 667370

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/paint/PaintInvalidator.h"
 
 #include "core/editing/FrameSelection.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Settings.h"
@@ skipping 424 matching lines @@
         PaintInvalidatorContext::ForcedSubtreeInvalidationChecking;
   }
 
   // TODO(crbug.com/490725): This is a workaround for the bug, to force
   // descendant to update visual rects on clipping change.
   if (!RuntimeEnabledFeatures::slimmingPaintV2Enabled() &&
       context.oldVisualRect != context.newVisualRect
       // Note that isLayoutView() below becomes unnecessary after the launch of
       // root layer scrolling.
       && (object.hasOverflowClip() || object.isLayoutView()) &&
-      !toLayoutBox(object).usesCompositedScrolling())
-    context.forcedSubtreeInvalidationFlags |=
-        PaintInvalidatorContext::ForcedSubtreeInvalidationRectUpdate;
+      !toLayoutBox(object).usesCompositedScrolling()) {
+//    context.forcedSubtreeInvalidationFlags |=
+//        PaintInvalidatorContext::ForcedSubtreeInvalidationRectUpdate;
+  }
 }
 
 void PaintInvalidator::processPendingDelayedPaintInvalidations() {
   for (auto target : m_pendingDelayedPaintInvalidations)
     target->getMutableForPainting().setShouldDoFullPaintInvalidation(
         PaintInvalidationDelayedFull);
 }
 
 }  // namespace blink