Use the original paint invalidation path for sync painting v1

third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp

Index: third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp b/third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp
index e6c10a9539fe3bb8b396b26f212a0bcb1c8449f6..42caaa37f2008b6ee3b531b473f4a417b68dfb83 100644
--- a/third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp
+++ b/third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp
@@ -116,7 +116,7 @@ void PaintController::invalidate(const DisplayItemClientWrapper& client, PaintIn
 {
     invalidateClient(client);
 
-    if (RuntimeEnabledFeatures::slimmingPaintSynchronizedPaintingEnabled()) {
+    if (RuntimeEnabledFeatures::slimmingPaintV2Enabled()) {
         Invalidation invalidation = { previousPaintInvalidationRect, paintInvalidationReason };
         if (!previousPaintInvalidationRect.isEmpty())
             m_invalidations.append(invalidation);
@@ -286,10 +286,15 @@ void PaintController::commitNewDisplayItems(GraphicsLayer* graphicsLayer)
             m_newPaintChunks.clear();
             return;
         }
+    }
+
+    if (RuntimeEnabledFeatures::slimmingPaintV2Enabled()) {
         for (const auto& invalidation : m_invalidations)
             graphicsLayer->setNeedsDisplayInRect(invalidation.rect, invalidation.invalidationReason);
         m_invalidations.clear();
         m_clientsCheckedPaintInvalidation.clear();
+    } else {
+        ASSERT(m_invalidations.isEmpty());
     }
 
     // These data structures are used during painting only.