Issue 3227 - Adjust unit tests for e10s-related element hiding changes

chrome/content/tests/elemhide.js

Index: chrome/content/tests/elemhide.js
===================================================================
--- a/chrome/content/tests/elemhide.js
+++ b/chrome/content/tests/elemhide.js
@@ -19,18 +19,19 @@
             '<div id="test1" class="testClass">foo</div>' +
             '<p id="test2" class="testClass">bar</p>' +
           '</body>';
         response.setStatusLine("1.1", "200", "OK");
         response.setHeader("Content-Type", "text/html; charset=utf-8");
         response.bodyOutputStream.write(body, body.length);
       });
 
-      frame = document.createElementNS("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul", "iframe");
+      frame = document.createElementNS("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul", "browser");
       frame.setAttribute("type", "content");
+      frame.setAttribute("disablehistory", "true");
       frame.style.visibility = "collapse";
       document.body.appendChild(frame);
     },
     teardown: function()
     {
       restoreFilterComponents.call(this);
       restorePrefs.call(this);
 
@@ -130,24 +131,40 @@
       else if (stage == 4)
         defaultMatcher.add(Filter.fromText("@@||localhost^$elemhide"));
 
       if (stage == 2 || stage == 4)
         expected = ["visible", "visible"];   // Second and forth runs are whitelisted, nothing should be hidden
 
       frame.addEventListener("abp:frameready", function()
       {
-        Utils.runAsync(function()
+        let frameScript = `
+          // The "load" event doesn't mean XBL bindings are done, these will
+          // take longer to load (async messaging). Only check visibility after
+          // sending a message to parent and receiving response.
+          addMessageListener("pong", function()
+          {
+            let visibility = [
+              content.document.getElementById("test1").offsetHeight > 0 ? "visible" : "hidden",
+              content.document.getElementById("test2").offsetHeight > 0 ? "visible" : "hidden"
+            ];
+            sendAsyncMessage("visibility", visibility);
+          });
+          sendAsyncMessage("ping");
+        `;
+        frame.messageManager.addMessageListener("ping", () => frame.messageManager.sendAsyncMessage("pong"));
+        frame.messageManager.addMessageListener("visibility", (message) =>
         {
-          let doc = frame.contentDocument;
-          equal(doc.getElementById("test1").offsetHeight > 0 ? "visible" : "hidden", expected[0], "First element visible");
-          equal(doc.getElementById("test2").offsetHeight > 0 ? "visible" : "hidden", expected[1], "Second element visible");
+          let visibility = message.data;
+          equal(visibility[0], expected[0], "First element visible");
+          equal(visibility[1], expected[1], "Second element visible");
 
           start();
         });
+        frame.messageManager.loadFrameScript("data:text/javascript," + encodeURIComponent(frameScript), false);
       }, false, true);
       frame.setAttribute("src", "http://localhost:1234/test");
     };
     FilterNotifier.addListener(listener);
 
     for (let filter_text of filters)
     {
       let filter = Filter.fromText(filter_text);