Let HTMLTablePartElement::findParentTable() about come across shadow boundary.

Source/core/html/HTMLTablePartElement.cpp

Index: Source/core/html/HTMLTablePartElement.cpp
diff --git a/Source/core/html/HTMLTablePartElement.cpp b/Source/core/html/HTMLTablePartElement.cpp
index d1c0849ab4fd8ea1e9ed4e3b08247ea8f0d437e8..25644e7413fb0c2a0b0be9d17a7cc6d984616a3e 100644
--- a/Source/core/html/HTMLTablePartElement.cpp
+++ b/Source/core/html/HTMLTablePartElement.cpp
@@ -31,6 +31,7 @@
 #include "core/css/CSSImageValue.h"
 #include "core/css/StylePropertySet.h"
 #include "core/dom/Document.h"
+#include "core/dom/NodeRenderingTraversal.h"
 #include "core/html/HTMLTableElement.h"
 #include "core/html/parser/HTMLParserIdioms.h"
 
@@ -84,9 +85,9 @@ void HTMLTablePartElement::collectStyleForPresentationAttribute(const QualifiedN
 
 HTMLTableElement* HTMLTablePartElement::findParentTable() const
 {
-    ContainerNode* parent = parentNode();
+    ContainerNode* parent = NodeRenderingTraversal::parent(this);
     while (parent && !parent->hasTagName(tableTag))
-        parent = parent->parentNode();
+        parent = NodeRenderingTraversal::parent(parent);
     return static_cast<HTMLTableElement*>(parent);
 }