diff -r 000000000000 -r 6474c204b198 dom/plugins/test/mochitest/pluginstream.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/plugins/test/mochitest/pluginstream.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,32 @@
+  SimpleTest.waitForExplicitFinish();
+
+  function frameLoaded() {
+    var testframe = document.getElementById('testframe');
+    var embed = document.getElementsByTagName('embed')[0];
+    if (undefined === embed)
+      embed = document.getElementsByTagName('object')[0];
+
+    // In the file:// URI case, this ends up being cross-origin.
+    // Skip these checks in that case.
+    if (testframe.contentDocument) {
+      var content = testframe.contentDocument.body.innerHTML;
+      if (!content.length)
+        return;
+
+      var filename = embed.getAttribute("src") ||
+          embed.getAttribute("geturl") ||
+          embed.getAttribute("geturlnotify") ||
+          embed.getAttribute("data");
+
+      var req = new XMLHttpRequest();
+      req.open('GET', filename, false);
+      req.overrideMimeType('text/plain; charset=x-user-defined');
+      req.send(null);
+      is(req.status, 200, "bad XMLHttpRequest status");
+      is(content, req.responseText.replace(/\r\n/g, "\n"),
+         "content doesn't match");
+    }
+
+    is(embed.getError(), "pass", "plugin reported error");
+    SimpleTest.finish();
+  }