Fix for calculation of event.path for closed mode shadow root

Source/core/events/TreeScopeEventContext.cpp

Index: Source/core/events/TreeScopeEventContext.cpp
diff --git a/Source/core/events/TreeScopeEventContext.cpp b/Source/core/events/TreeScopeEventContext.cpp
index 22a8cacb23a3b54757233f7eefefd745981e005d..c94a8ff9b299c5b252a357130e0653b3d4c5348b 100644
--- a/Source/core/events/TreeScopeEventContext.cpp
+++ b/Source/core/events/TreeScopeEventContext.cpp
@@ -34,6 +34,36 @@
 
 namespace blink {
 
+bool TreeScopeEventContext::shouldIncludeTreeScope(const TreeScopeEventContext& other)
+{
+    const Node& rootNode = other.rootNode();
+
+    // Exclude nodes in UA shadow.  E.g. <details> distributes elements under its tree.
+    if (rootNode.isShadowRoot() && (toShadowRoot(rootNode).type() == ShadowRootType::UserAgent))
+        return false;
+
+    // Exclude closed nodes if necessary.
+
+    // If a node is in a closed shadow root, or in a tree whose ancestor has a closed shadow root,
+    // it should not be visible to nodes above the closed shadow root.
+
+    // (1) If |other| is an ancestor in tree-of-trees, include it.
+    if (other.isInclusiveAncestorOf(*this))
+        return true;
+
+    // (2) If no closed shadow root in ancestors of |other|, include it.
+    if (!other.containingClosedShadowTree())
+        return true;
+
+    // (3) If |other| is descendent of |this|, exclude if any closed shadow root in between.
+    if (other.isDescendantOf(*this))
+        return !other.containingClosedShadowTree()->isDescendantOf(*this);
+
+    // (4) |this| and |other| must be in exclusive branches.
+    ASSERT(isExclusivePartOf(other));
+    return false;
+}
+
 WillBeHeapVector<RefPtrWillBeMember<EventTarget>>& TreeScopeEventContext::ensureEventPath(EventPath& path)
 {
     if (m_eventPath)
@@ -42,11 +72,9 @@ WillBeHeapVector<RefPtrWillBeMember<EventTarget>>& TreeScopeEventContext::ensure
     m_eventPath = adoptPtrWillBeNoop(new WillBeHeapVector<RefPtrWillBeMember<EventTarget>>());
     LocalDOMWindow* window = path.windowEventContext().window();
     m_eventPath->reserveCapacity(path.size() + (window ? 1 : 0));
+
     for (size_t i = 0; i < path.size(); ++i) {
-        Node& rootNode = path[i].treeScopeEventContext().rootNode();
-        if (rootNode.isShadowRoot() && (toShadowRoot(rootNode).type() == ShadowRootType::OpenByDefault || toShadowRoot(rootNode).type() == ShadowRootType::Open))
-            m_eventPath->append(path[i].node());
-        else if (path[i].treeScopeEventContext().isInclusiveAncestorOf(*this))
+        if (shouldIncludeTreeScope(path[i].treeScopeEventContext()))
             m_eventPath->append(path[i].node());
     }
     if (window)
@@ -69,6 +97,7 @@ PassRefPtrWillBeRawPtr<TreeScopeEventContext> TreeScopeEventContext::create(Tree
 TreeScopeEventContext::TreeScopeEventContext(TreeScope& treeScope)
     : m_treeScope(treeScope)
     , m_rootNode(treeScope.rootNode())
+    , m_containingClosedShadowTree(nullptr)
     , m_preOrder(-1)
     , m_postOrder(-1)
 {
@@ -84,18 +113,21 @@ DEFINE_TRACE(TreeScopeEventContext)
     visitor->trace(m_relatedTarget);
     visitor->trace(m_eventPath);
     visitor->trace(m_touchEventContext);
+    visitor->trace(m_containingClosedShadowTree);
 #if ENABLE(OILPAN)
     visitor->trace(m_children);
 #endif
 }
 
-int TreeScopeEventContext::calculatePrePostOrderNumber(int orderNumber)
+int TreeScopeEventContext::calculateTreeOrderAndFindClosedTrees(int orderNumber, TreeScopeEventContext* parentClosedTreeScopeEventContext)
 {
     m_preOrder = orderNumber;
+    m_containingClosedShadowTree = (rootNode().isShadowRoot() && toShadowRoot(rootNode()).type() == ShadowRootType::Closed) ? this : parentClosedTreeScopeEventContext;
     for (size_t i = 0; i < m_children.size(); ++i)
-        orderNumber = m_children[i]->calculatePrePostOrderNumber(orderNumber + 1);
+        orderNumber = m_children[i]->calculateTreeOrderAndFindClosedTrees(orderNumber + 1, containingClosedShadowTree());
     m_postOrder = orderNumber + 1;
+
     return orderNumber + 1;
 }
 
-}
+} // namespace blink