Add a test for event.path() used with a user agent shadow tree.

LayoutTests/fast/dom/shadow/event-path-for-user-agent-shadow-tree-expected.txt

Index: LayoutTests/fast/dom/shadow/event-path-for-user-agent-shadow-tree-expected.txt
diff --git a/LayoutTests/fast/dom/shadow/event-path-for-user-agent-shadow-tree-expected.txt b/LayoutTests/fast/dom/shadow/event-path-for-user-agent-shadow-tree-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..97c738fd60675c4c4e68c57bba0d5a8d72aa31f8
--- /dev/null
+++ b/LayoutTests/fast/dom/shadow/event-path-for-user-agent-shadow-tree-expected.txt
@@ -0,0 +1,29 @@
+ 
+Dispaching a click event on #details-child
+
+event.path() on node #details-child
+#details-child, #details, #sandbox, [object HTMLBodyElement], [object HTMLHtmlElement], [object HTMLDocument], length: 6
+
+event.path() on node #details
+#details-child, #details, #sandbox, [object HTMLBodyElement], [object HTMLHtmlElement], [object HTMLDocument], length: 6
+
+event.path() on node #sandbox
+#details-child, #details, #sandbox, [object HTMLBodyElement], [object HTMLHtmlElement], [object HTMLDocument], length: 6
+
+Dispaching a click event on #summary-child
+
+event.path() on node #summary-child
+#summary-child, #summary, #details, #sandbox, [object HTMLBodyElement], [object HTMLHtmlElement], [object HTMLDocument], length: 7
+
+event.path() on node #summary
+#summary-child, #summary, #details, #sandbox, [object HTMLBodyElement], [object HTMLHtmlElement], [object HTMLDocument], length: 7
+
+event.path() on node #details
+#summary-child, #summary, #details, #sandbox, [object HTMLBodyElement], [object HTMLHtmlElement], [object HTMLDocument], length: 7
+
+event.path() on node #sandbox
+#summary-child, #summary, #details, #sandbox, [object HTMLBodyElement], [object HTMLHtmlElement], [object HTMLDocument], length: 7
+PASS successfullyParsed is true
+
+TEST COMPLETE
+