wpt: Support http://host:80/ at EventListener / incumbent test

MessageEvent's origin attribute will be
    http://hostname
instead of
    http://hostname:80
in case that the port number is HTTP standard port number, i.e. 80.

Usually this is not a problem because wptserve runs with port=8001
by default, but w3c-test.org runs with port=80.
http://w3c-test.org/dom/events/EventListener-incumbent-global-2.sub.html

This patch supports such a case.

Bug: 622974
Change-Id: I4567de3f5f12ae42c222229eafafecbbe72129e0

dom/events/EventListener-incumbent-global-subsubframe.sub.html

@@ -8,10 +8,15 @@
     if (e.data == "sendclick") {
       document.body.click();
     } else {
+      let expectedOrigin = "{{location[scheme]}}://{{domains[www1]}}:{{ports[http][0]}}";
+      if ("{{location[scheme]}}" == "http" &&
+          "{{ports[http][0]}}" == "80") {
+        expectedOrigin = "{{location[scheme]}}://{{domains[www1]}}";
+      }
       parent.postMessage(
         {
           actual: e.origin,
-          expected: "{{location[scheme]}}://{{domains[www1]}}:{{ports[http][0]}}",
+          expected: expectedOrigin,
           reason: "Incumbent should have been the caller of addEventListener()"
         },
         "*")