Make assignedSlot return null for a slot in a closed shadow tree

third_party/WebKit/Source/core/dom/Node.cpp

Index: third_party/WebKit/Source/core/dom/Node.cpp
diff --git a/third_party/WebKit/Source/core/dom/Node.cpp b/third_party/WebKit/Source/core/dom/Node.cpp
index 51c634b97c06438ad5a9496c91e535f0089371b2..173abe1c5fecceb9eb19114e38c3e37464f53520 100644
--- a/third_party/WebKit/Source/core/dom/Node.cpp
+++ b/third_party/WebKit/Source/core/dom/Node.cpp
@@ -2216,7 +2216,7 @@ HTMLSlotElement* Node::assignedSlot() const
     if (!parent)
         return nullptr;
     if (ElementShadow* shadow = parent->shadow()) {
-        if (shadow->isV1())
+        if (shadow->isV1() && shadow->isOpen())
             return shadow->assignedSlotFor(*this);
     }
     return nullptr;