testharnessreport: Hide unnecessary elements for JS tests

LayoutTests/resources/testharnessreport.js

 /*
  * THIS FILE INTENTIONALLY LEFT BLANK
  *
  * More specifically, this file is intended for vendors to implement
  * code needed to integrate testharness.js tests with their own test systems.
  *
  * Typically such integration will attach callbacks when each test is
  * has run, using add_result_callback(callback(test)), or when the whole test file has
  * completed, using add_completion_callback(callback(tests, harness_status)).
  *
@@ skipping 29 matching lines @@
 
 /* If the test has a meta tag named flags and the content contains "dom", then it's a CSSWG test.
  */
 function isCSSWGTest() {
     var flags = document.querySelector('meta[name=flags]'),
         content = flags ? flags.getAttribute('content') : null;
 
     return content && content.match(/\bdom\b/);
 }
 
+function isJSTest() {
+    return !!document.querySelector('script[src*="/resources/testharness"]');
+}
+
 /*  Using a callback function, test results will be added to the page in a
 *   manner that allows dumpAsText to produce readable test results
 */
 add_completion_callback(function (tests, harness_status) {
 
     // Create element to hold results
     var results = document.createElement("pre");
 
     // Declare result string
     var resultStr = "This is a testharness.js-based test.\n";
@@ skipping 27 matching lines @@
         }
     }
     resultStr += "Harness: the test ran to completion.\n";
 
     // Set results element's textContent to the results string
     results.textContent = resultStr;
 
     function done() {
         if (self.testRunner) {
             var logDiv = document.getElementById('log');
-            if (isCSSWGTest() && logDiv) {
+            if ((isCSSWGTest() || isJSTest()) && logDiv) {
                 // Assume it's a CSSWG style test, and anything other than the log div isn't
                 // material to the testrunner output, so should be hidden from the text dump
                 for (var i = 0; i < document.body.children.length; i++) {
                     if (document.body.children[i] === logDiv) continue;
 
                     document.body.children[i].style.visibility = "hidden";
                 }
             }
         }
 
         // Add results element to document
         document.body.appendChild(results);
 
         if (self.testRunner)
             testRunner.notifyDone();
     }
 
     if (!document.body || document.readyState === 'loading') {
         window.addEventListener('load', done);
     } else {
         done();
     }
 });