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

LayoutTests/fast/dom/shadow/event-path-closed-shadowroot-expected.txt

+Event.path should include only unclosed elements.
+
+Dispaching a click event on #target_open, listening on #target_open.
+PASS eventPath.length is 9
+
+event.path for #target_open:
+#target_open, [object ShadowRoot], #inner_open, [object ShadowRoot], #host_open, [object HTMLBodyElement], [object HTMLHtmlElement], [object HTMLDocument], [object Window], length: 9
+
+Dispaching a click event on #target_closed, listening on #target_closed.
+PASS eventPath.length is 9
+
+event.path for #target_closed:
+#target_closed, [object ShadowRoot], #inner_closed, [object ShadowRoot], #host_closed, [object HTMLBodyElement], [object HTMLHtmlElement], [object HTMLDocument], [object Window], length: 9
+
+Dispaching a click event on #target_open, listening on document.body.
+PASS eventPath.length is 9
+
+event.path for #target_open:
+#target_open, [object ShadowRoot], #inner_open, [object ShadowRoot], #host_open, [object HTMLBodyElement], [object HTMLHtmlElement], [object HTMLDocument], [object Window], length: 9
+
+Dispaching a click event on #target_closed, listening on document.body.
+PASS eventPath.length is 5
+
+event.path for #target_closed:
+#host_closed, [object HTMLBodyElement], [object HTMLHtmlElement], [object HTMLDocument], [object Window], length: 5
+PASS successfullyParsed is true
+
+TEST COMPLETE
+