Remove Event.relatedTargetScoped and update event path calculation for relatedTarget

third_party/WebKit/LayoutTests/shadow-dom/resources/shadow-dom.js

 function removeWhiteSpaceOnlyTextNodes(node)
 {
     for (var i = 0; i < node.childNodes.length; i++) {
         var child = node.childNodes[i];
         if (child.nodeType === Node.TEXT_NODE && child.nodeValue.trim().length == 0) {
             node.removeChild(child);
             i--;
         } else if (child.nodeType === Node.ELEMENT_NODE || child.nodeType === Node.DOCUMENT_FRAGMENT_NODE) {
             removeWhiteSpaceOnlyTextNodes(child);
         }
@@ skipping 112 matching lines @@
                   event.relatedTarget ? labelFor(event.relatedTarget) : null,
                   event.composedPath().map((n) => {
                     return labelFor(n);
                   })]);
       });
     }
   }
   target.dispatchEvent(event);
   return log;
 }
+
+// This function assumes that testharness.js is available.
+function assert_event_path_equals(actual, expected) {
+  assert_equals(actual.length, expected.length);
+  for (let i = 0; i < actual.length; ++i) {
+    assert_equals(actual[i][0], expected[i][0], 'currentTarget at ' + i + ' should be same');
+    assert_equals(actual[i][1], expected[i][1], 'relatedTarget at ' + i + ' should be same');
+    assert_array_equals(actual[i][2], expected[i][2], 'composedPath at ' + i + ' should be same');
+  }
+}