Experimental: Change LazyReattachIfAttached to SetChildNeedsStyleRecalc

third_party/WebKit/Source/core/dom/shadow/ElementShadow.cpp

Index: third_party/WebKit/Source/core/dom/shadow/ElementShadow.cpp
diff --git a/third_party/WebKit/Source/core/dom/shadow/ElementShadow.cpp b/third_party/WebKit/Source/core/dom/shadow/ElementShadow.cpp
index 8508993596ce62a25cc7ad42f6d81113ddb8f05f..c2719b46de20dc8a6b162babcaf78b434f7d4b57 100644
--- a/third_party/WebKit/Source/core/dom/shadow/ElementShadow.cpp
+++ b/third_party/WebKit/Source/core/dom/shadow/ElementShadow.cpp
@@ -83,8 +83,11 @@ ShadowRoot& ElementShadow::AddShadowRoot(Element& shadow_host,
   if (type == ShadowRootType::V0) {
     SetNeedsDistributionRecalc();
   } else {
-    for (Node& child : NodeTraversal::ChildrenOf(shadow_host))
-      child.LazyReattachIfAttached();
+    for (Node& child : NodeTraversal::ChildrenOf(shadow_host)) {
+      child.SetNeedsStyleRecalc(
+          kSubtreeStyleChange,
+          StyleChangeReasonForTracing::Create(StyleChangeReason::kShadow));
+    }
   }
 
   shadow_root->InsertedInto(&shadow_host);