Support the essential part of Shadow DOM v1

third_party/WebKit/Source/core/testing/Internals.cpp

Index: third_party/WebKit/Source/core/testing/Internals.cpp
diff --git a/third_party/WebKit/Source/core/testing/Internals.cpp b/third_party/WebKit/Source/core/testing/Internals.cpp
index ef4671f7d9f7abd770693102274cd2f66a78308b..e5990025a67af8327900dbe3aa77454425d5462f 100644
--- a/third_party/WebKit/Source/core/testing/Internals.cpp
+++ b/third_party/WebKit/Source/core/testing/Internals.cpp
@@ -619,6 +619,16 @@ Node* Internals::previousInComposedTree(Node* node, ExceptionState& exceptionSta
     return ComposedTreeTraversal::previous(*node);
 }
 
+Node* Internals::parentInComposedTree(Node* node, ExceptionState& exceptionState)
+{
+    ASSERT(node);
+    if (!node->canParticipateInComposedTree()) {
+        exceptionState.throwDOMException(InvalidAccessError, "The node argument doesn't particite in the composed tree.");
+        return nullptr;
+    }
+    return ComposedTreeTraversal::parent(*node);
+}
+
 String Internals::elementLayoutTreeAsText(Element* element, ExceptionState& exceptionState)
 {
     ASSERT(element);