Overlay expected and actual repaint rects for LayoutTests.

LayoutTests/fast/harness/resources/results-test.js

 // To run these tests, load json_results.html in a browser.
 // You should see a series of PASS lines.
 if (window.testRunner)
     testRunner.dumpAsText();
 
 var testStyles = document.createElement('style');
 testStyles.innerText = ".test-pass { color: green; } .test-fail { color: red; }";
 document.querySelector('head').appendChild(testStyles);
 
 var g_testIndex = 0;
@@ skipping 781 matching lines @@
     });
 
     results = mockResults();
     results.tests['foo/bar-image.html'] = mockExpectation('PASS', 'TEXT IMAGE');
     results.pixel_tests_enabled = false;
     runTest(results, function() {
         assertTrue(!document.getElementById('results-table'));
         assertTrue(document.querySelector('#flaky-tests-table td:nth-child(3) a').getAttribute('href') == 'retries/foo/bar-image-diffs.html');
     });
 
+    results = mockResults();
+    results.tests['foo'] = mockExpectation('PASS', 'TEXT');
+    results.tests['foo'].has_repaint_overlay = true;
+    runTest(results, function() {
+        assertTrue(document.querySelector('tbody td:nth-child(2)').textContent.indexOf('overlay') != -1);
+    })
+
     document.body.innerHTML = '<pre>' + g_log.join('\n') + '</pre>';
 }
 
 var originalGeneratePage = generatePage;
 generatePage = runTests;