Bug 1384387 - Clear frame's invalidation state bits in layers-free mode. r=kats

MozReview-Commit-ID: DRv5IcRQVs0

--HG--
extra : rebase_source : 9235e8f45a5fe7a200e63b572be61e9906ded5cc

layout/painting/nsDisplayList.cpp

@@ -2107,6 +2107,17 @@ already_AddRefed<LayerManager> nsDisplayList::PaintRoot(nsDisplayListBuilder* aB
     MaybeSetupTransactionIdAllocator(layerManager, presContext);
     bool temp = aBuilder->SetIsCompositingCheap(layerManager->IsCompositingCheap());
     static_cast<WebRenderLayerManager*>(layerManager.get())->EndTransactionWithoutLayer(this, aBuilder);
+
+    // For layers-free mode, we check the invalidation state bits in the EndTransaction.
+    // So we clear the invalidation state bits after EndTransaction.
+    if (widgetTransaction ||
+        // SVG-as-an-image docs don't paint as part of the retained layer tree,
+        // but they still need the invalidation state bits cleared in order for
+        // invalidation for CSS/SMIL animation to work properly.
+        (document && document->IsBeingUsedAsImage())) {
+      frame->ClearInvalidationStateBits();
+    }
+
     aBuilder->SetIsCompositingCheap(temp);
     return layerManager.forget();
   }