--- a/testing/web-platform/tests/css/css-transitions/CSSTransition-startTime.tentative.html
+++ b/testing/web-platform/tests/css/css-transitions/CSSTransition-startTime.tentative.html
@@ -35,17 +35,17 @@ promise_test(async t => {
 
   let animations = div.getAnimations();
   assert_equals(animations.length, 2);
   await waitForAllAnimations(animations);
 
   assert_equals(animations[0].startTime, animations[1].startTime,
     'CSS transitions started together have the same start time');
 
-  await waitForFrame();
+  await waitForAnimationFrames(1);
 
   div.style.backgroundColor = 'green';
 
   animations = div.getAnimations();
   assert_equals(animations.length, 3);
   await waitForAllAnimations(animations);
 
   assert_less_than(animations[1].startTime, animations[2].startTime,

--- a/testing/web-platform/tests/css/css-transitions/properties-value-001.html
+++ b/testing/web-platform/tests/css/css-transitions/properties-value-001.html
@@ -54,17 +54,17 @@
             // for testing, limit to a couple of iterations
             // tests = tests.slice(10, 30);
             // or filter using one of:
             // tests = filterPropertyTests(tests, "background-color color(rgba)");
             // tests = filterPropertyTests(tests, ["background-color color(rgba)", ...]);
             // tests = filterPropertyTests(tests, /^background-color/);
 
             // general transition-duration
-            var duration = '0.5s';
+            var duration = '2s';
 
             runParallelAsyncHarness({
                 // array of test data
                 tests: tests,
                 // the number of tests to run in parallel
                 testsPerSlice: 50,
                 // milliseconds to wait before calling teardown and ending test
                 duration: parseFloat(duration) * 1000,

--- a/testing/web-platform/tests/css/css-transitions/properties-value-002.html
+++ b/testing/web-platform/tests/css/css-transitions/properties-value-002.html
@@ -56,17 +56,17 @@
             // for testing, limit to a couple of iterations
             // tests = tests.slice(10, 30);
             // or filter using one of:
             // tests = filterPropertyTests(tests, "background-color color(rgba)");
             // tests = filterPropertyTests(tests, ["background-color color(rgba)", ...]);
             // tests = filterPropertyTests(tests, /^background-color/);
 
             // general transition-duration
-            var duration = '0.5s';
+            var duration = '2s';
 
             runParallelAsyncHarness({
                 // array of test data
                 tests: tests,
                 // the number of tests to run in parallel
                 testsPerSlice: 50,
                 // milliseconds to wait before calling teardown and ending test
                 duration: parseFloat(duration) * 1000,

--- a/testing/web-platform/tests/css/css-transitions/properties-value-003.html
+++ b/testing/web-platform/tests/css/css-transitions/properties-value-003.html
@@ -58,17 +58,17 @@
             // for testing, limit to a couple of iterations
             // tests = tests.slice(10, 30);
             // or filter using one of:
             // tests = filterPropertyTests(tests, "background-color color(rgba)");
             // tests = filterPropertyTests(tests, ["background-color color(rgba)", ...]);
             // tests = filterPropertyTests(tests, /^background-color/);
 
             // general transition-duration
-            var duration = '0.5s';
+            var duration = '2s';
 
             runParallelAsyncHarness({
                 // array of test data
                 tests: tests,
                 // the number of tests to run in parallel
                 testsPerSlice: 50,
                 // milliseconds to wait before calling teardown and ending test
                 duration: parseFloat(duration) * 1000,

--- a/testing/web-platform/tests/css/css-transitions/properties-value-auto-001.html
+++ b/testing/web-platform/tests/css/css-transitions/properties-value-auto-001.html
@@ -56,25 +56,25 @@
             // for testing, limit to a couple of iterations
             // tests = tests.slice(10, 30);
             // or filter using one of:
             // tests = filterPropertyTests(tests, "background-color color(rgba)");
             // tests = filterPropertyTests(tests, ["background-color color(rgba)", ...]);
             // tests = filterPropertyTests(tests, /^background-color/);
 
             // general transition-duration
-            var duration = '0.5s';
+            var duration = '2s';
 
             runParallelAsyncHarness({
                 // array of test data
                 tests: tests,
                 // the number of tests to run in parallel
                 testsPerSlice: 50,
                 // milliseconds to wait before calling teardown and ending test
-                duration: parseFloat(duration) * 1000,
+                duration: parseFloat(duration) * 1200,
                 // prepare individual test
                 setup: function(data, options) {
                     var styles = {
                         '.fixture': {},
 
                         '.container': data.parentStyle,
                         '.container.to': {},
                         '.container.how': {},

--- a/testing/web-platform/tests/css/css-transitions/properties-value-implicit-001.html
+++ b/testing/web-platform/tests/css/css-transitions/properties-value-implicit-001.html
@@ -57,17 +57,17 @@
             // for testing, limit to a couple of iterations
             // tests = tests.slice(10, 30);
             // or filter using one of:
             // tests = filterPropertyTests(tests, "background-color color(rgba)");
             // tests = filterPropertyTests(tests, ["background-color color(rgba)", ...]);
             // tests = filterPropertyTests(tests, /^background-color/);
 
             // general transition-duration
-            var duration = '0.5s';
+            var duration = '2s';
 
             runParallelAsyncHarness({
                 // array of test data
                 tests: tests,
                 // the number of tests to run in parallel
                 testsPerSlice: 50,
                 // milliseconds to wait before calling teardown and ending test
                 duration: parseFloat(duration) * 1000,

--- a/testing/web-platform/tests/css/css-transitions/properties-value-inherit-001.html
+++ b/testing/web-platform/tests/css/css-transitions/properties-value-inherit-001.html
@@ -57,17 +57,17 @@
             // for testing, limit to a couple of iterations
             // tests = tests.slice(10, 30);
             // or filter using one of:
             // tests = filterPropertyTests(tests, "background-color color(rgba)");
             // tests = filterPropertyTests(tests, ["background-color color(rgba)", ...]);
             // tests = filterPropertyTests(tests, /^background-color/);
 
             // general transition-duration
-            var duration = '0.5s';
+            var duration = '2s';
 
             runParallelAsyncHarness({
                 // array of test data
                 tests: tests,
                 // the number of tests to run in parallel
                 testsPerSlice: 50,
                 // milliseconds to wait before calling teardown and ending test
                 duration: parseFloat(duration) * 1000,

--- a/testing/web-platform/tests/css/css-transitions/properties-value-inherit-002.html
+++ b/testing/web-platform/tests/css/css-transitions/properties-value-inherit-002.html
@@ -58,17 +58,17 @@
             // for testing, limit to a couple of iterations
             // tests = tests.slice(10, 30);
             // or filter using one of:
             // tests = filterPropertyTests(tests, "background-color color(rgba)");
             // tests = filterPropertyTests(tests, ["background-color color(rgba)", ...]);
             // tests = filterPropertyTests(tests, /^background-color/);
 
             // general transition-duration
-            var duration = '0.5s';
+            var duration = '2s';
 
             runParallelAsyncHarness({
                 // array of test data
                 tests: tests,
                 // the number of tests to run in parallel
                 testsPerSlice: 50,
                 // milliseconds to wait before calling teardown and ending test
                 duration: parseFloat(duration) * 1000,

--- a/testing/web-platform/tests/css/css-transitions/properties-value-inherit-003.html
+++ b/testing/web-platform/tests/css/css-transitions/properties-value-inherit-003.html
@@ -57,17 +57,17 @@
             // for testing, limit to a couple of iterations
             // tests = tests.slice(10, 30);
             // or filter using one of:
             // tests = filterPropertyTests(tests, "background-color color(rgba)");
             // tests = filterPropertyTests(tests, ["background-color color(rgba)", ...]);
             // tests = filterPropertyTests(tests, /^background-color/);
 
             // general transition-duration
-            var duration = '0.5s';
+            var duration = '2s';
 
             runParallelAsyncHarness({
                 // array of test data
                 tests: tests,
                 // the number of tests to run in parallel
                 testsPerSlice: 50,
                 // milliseconds to wait before calling teardown and ending test
                 duration: parseFloat(duration) * 1000,

--- a/testing/web-platform/tests/css/css-transitions/pseudo-elements-001.html
+++ b/testing/web-platform/tests/css/css-transitions/pseudo-elements-001.html
@@ -79,17 +79,17 @@
                     property: 'padding-left',
                     flags: {},
                     from: {'padding-left': '1px', 'content': '"1"'},
                     to: {'padding-left': '10px', 'content': '"2"'}
                 }
             ];
 
             // general transition-duration
-            var duration = '0.5s';
+            var duration = '2s';
 
             runParallelAsyncHarness({
                 // array of test data
                 tests: tests,
                 // the number of tests to run in parallel
                 testsPerSlice: 50,
                 // milliseconds to wait before calling teardown and ending test
                 duration: parseFloat(duration) * 1000,

--- a/testing/web-platform/tests/css/css-transitions/support/runParallelAsyncHarness.js
+++ b/testing/web-platform/tests/css/css-transitions/support/runParallelAsyncHarness.js
@@ -108,18 +108,18 @@ root.runParallelAsyncHarness = function(
         tests.forEach(function(data) {
             cases.forEach(function(name) {
                 data.cases[name].step(function() {
                     (options.cases[name].start || noop)(data.cases[name], data, options);
                 });
             });
         });
 
-        // conclude test (possibly abort)
-        setTimeout(function() {
+        // conclude slice (possibly abort)
+        var concludeSlice = function() {
             tests.forEach(function(data) {
                 // perform individual "done" test-case
                 cases.forEach(function(name) {
                     data.cases[name].step(function() {
                         (options.cases[name].done || noop)(data.cases[name], data, options);
                     });
                 });
                 // clean up after individual test
@@ -130,16 +130,19 @@ root.runParallelAsyncHarness = function(
                 });
             });
 
             // finish the test for current slice of tests
             (options.sliceDone || noop)(options, tests);
 
             // next test please, give the browser 50ms to do catch its breath
             setTimeout(runLoop, 50);
-        }, duration);
+        }
+
+        // wait on RAF before cleanup to make sure all queued event handlers have run
+        setTimeout(function() {requestAnimationFrame(concludeSlice)},duration);
     }
 
     // allow DOMContentLoaded before actually doing something
     setTimeout(runLoop, 100);
 };
 
 })(window);

deleted file mode 100644
--- a/testing/web-platform/tests/css/css-transitions/transitions-animatable-properties-01.html
+++ /dev/null
@@ -1,179 +0,0 @@
-<!DOCTYPE html>
-<html>
-<!-- Submitted from TestTWF Paris -->
-  <head>
-    <meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type">
-    <title> CSS Transitions: Animatable CSS properties </title>
-    <meta name="assert" content="Check that all animatable CSS properties are animatable and then accepted by the 'transition-property' property">
-    <meta name="timeout" content="long">
-    <link rel="author" title="Daniel Glazman" href="mailto:daniel.glazman@disruptive-innovations.com">
-    <link rel="help" href="http://www.w3.org/TR/css3-transitions/#transitions">
-    <link rel="help" href="http://www.w3.org/TR/css3-transitions/#animatable-properties">
-    <link rel="reviewer" title="Alan Stearns" href="mailto:stearns@adobe.com">
-
-    <style type="text/css">
-
-      html, body { margin: 0px; padding: 0px; }
-
-      .w50vw { width: 50vw; )
-      .h50vh { height: 50vh; }
-
-      .w50vm { width: 50vm; }
-      .h50vm { height: 50vm; }
-    </style>
-
-    <script src="/resources/testharness.js" type="text/javascript"></script>
-    <script src="/resources/testharnessreport.js" type="text/javascript"></script>
-
-    <style type="text/css" id="newStyles"></style>
-  </head>
-  <body>
-    <p>Check that all animatable CSS properties are animatable and
-      then accepted by the 'transition-property' property.<br>
-    </p>
-
-    <p id="testP">THIS PROSE NEEDED FOR TEST ITSELF</p>
-
-    <div id="log"></div><a href="transitions-animatable-properties-01.html" id="" title="transitions-animatable-properties-01">transitions-animatable-properties-01</a>
-
-    <script type="text/javascript">
-      var kANIMATABLE_CSS_PROPERTIES = [
-          ["background-color",    "white",                      "rgb(0, 128, 0)",               "", false],
-          ["background-position", "0px 0px",                    "100% 100%",                    "", false],
-          ["border-color",        "white",                      "rgb(0, 128, 0)",               "", false],
-          ["border-bottom-color", "white",                      "rgb(0, 128, 0)",               "", false],
-          ["border-bottom-width", "0px",                        "10px",                         "border-style: solid; border-color: black", false],
-          ["border-left-color",   "white",                      "rgb(0, 128, 0)",               "", false],
-          ["border-left-width",   "0px",                        "10px",                         "border-style: solid; border-color: black", false],
-          ["border-right-color",  "white",                      "rgb(0, 128, 0)",               "", false],
-          ["border-right-width",  "0px",                        "10px",                         "border-style: solid; border-color: black", false],
-          ["border-spacing",      "0px",                        "10px 15px",                    "", false],
-          ["border-top-color",    "white",                      "rgb(0, 128, 0)",               "", false],
-          ["border-top-width",    "0px",                        "10px",                         "border-style: solid; border-color: black", false],
-          ["bottom",              "0px",                        "10px",                         "", false],
-          ["clip",                "rect(0px, 0px, 10px, 10px)", "rect(10px, 10px, 20px, 20px)", "", false],
-          ["color",               "white",                      "rgb(0, 128, 0)",               "", false],
-          ["crop",                "rect(0px, 0px, 10px, 10px)", "rect(10px 10px 20px 20px)",    "", false],
-          ["font-size",           "12pt",                       "32px",                         "", false],
-          ["font-weight",         "400",                        "900",                          "", false],
-          ["height",              "1em",                        "64px",                         "", false],
-          ["left",                "0px",                        "10px",                         "", false],
-          ["letter-spacing",      "1em",                        "64px",                         "", false],
-          ["line-height",         "1em",                        "64px",                         "", false],
-          ["margin-bottom",       "0px",                        "10px",                         "", false],
-          ["margin-left",         "0px",                        "10px",                         "", false],
-          ["margin-right",        "0px",                        "10px",                         "", false],
-          ["margin-top",          "0px",                        "10px",                         "", false],
-          ["max-height",          "0px",                        "10px",                         "", false],
-          ["max-width",           "0px",                        "10px",                         "", false],
-          ["min-height",          "0px",                        "10px",                         "", false],
-          ["min-width",           "0px",                        "10px",                         "", false],
-          ["opacity",             "0",                          "1",                            "", false],
-          ["outline-color",       "white",                      "rgb(0, 128, 0)",               "", false],
-          ["outline-offset",      "0px",                        "10px",                         "", false],
-          ["outline-width",       "0px",                        "10px",                         "outline-style: solid; outline-style: black", false],
-          ["padding-bottom",      "0px",                        "10px",                         "", false],
-          ["padding-left",        "0px",                        "10px",                         "", false],
-          ["padding-right",       "0px",                        "10px",                         "", false],
-          ["padding-top",         "0px",                        "10px",                         "", false],
-          ["right",               "0px",                        "10px",                         "", false],
-          ["text-indent",         "0px",                        "10px",                         "", false],
-          ["text-shadow",         "orange 0 -2px",              "rgb(0, 128, 0) 0px 2px 0px",   "", false],
-          ["top",                 "0px",                        "10px",                         "", false],
-          ["vertical-align",      "0px",                        "10px",                         "", false],
-          ["visibility",          "visible",                    "hidden",                       "", true],
-          ["width",               "0px",                        "10px",                         "", false],
-          ["word-spacing",        "0px",                        "10px",                         "", false],
-          ["z-index",             "1",                           "10",                          "", false]
-      ];
-
-      // page timeout
-      var kTIMEOUT = 3000000;
-
-      var p = document.getElementById("testP");
-      var style = document.getElementById("newStyles");
-
-      var testsIntermediate = [];
-      var testsEnd = [];
-
-      setup({timeout: kTIMEOUT});
-
-      // create all the tests we need
-      for (var i = 0; i < kANIMATABLE_CSS_PROPERTIES.length; i++) {
-        testsIntermediate.push(async_test(kANIMATABLE_CSS_PROPERTIES[i][0] + " intermediate"));
-        testsEnd.push(async_test(kANIMATABLE_CSS_PROPERTIES[i][0] + " end"));
-      }
-
-      // getComputedStyle helper
-      function gCS(aProperty)
-      {
-        return document.defaultView
-               .getComputedStyle(p, "")
-               .getPropertyValue(aProperty);
-      }
-
-      function Scheduler(aIndex)
-      {
-        if (aIndex >= kANIMATABLE_CSS_PROPERTIES.length) // we're done here
-          return;
-
-        var property   = kANIMATABLE_CSS_PROPERTIES[aIndex][0];
-        var startValue = kANIMATABLE_CSS_PROPERTIES[aIndex][1];
-        var endValue   = kANIMATABLE_CSS_PROPERTIES[aIndex][2];
-        var extras     = kANIMATABLE_CSS_PROPERTIES[aIndex][3];
-        var discrete   = kANIMATABLE_CSS_PROPERTIES[aIndex][4];
-
-        // create a style rule
-        var s = "#testP { ";
-        s += property + ": " + startValue + ";\n";
-        s += "transition-property: " + property + ";\n";
-        s += "transition-duration: 0.5s;\n";
-        s += "transition-delay: 0s;\n";
-        s += "transition-timing-function: linear;\n";
-        s += extras;
-        s += "}";
-        style.textContent = s;
-
-        // flush styles
-        gCS(property);
-
-        // set property to endValue
-        p.setAttribute("style", property + ": " + endValue + "; ");
-
-        // test for intermediate value
-        setTimeout(function()
-                   {
-                     testsIntermediate[aIndex].step(function()
-                                         {
-                                           var cs = gCS(property);
-                                           if (discrete) {
-                                             assert_equals(cs, startValue);
-                                           }
-                                           else {
-                                             assert_true((cs != startValue) && (null != cs));
-                                           }
-                                         });
-                     testsIntermediate[aIndex].done();
-                   }, 250);
-
-        // test for final value
-        setTimeout(function()
-                   {
-                     testsEnd[aIndex].step(function()
-                                           {
-                                             var cs = gCS(property);
-                                             assert_equals(cs, endValue);
-                                           }
-                                          );
-                     testsEnd[aIndex].done();
-                     Scheduler(aIndex + 1);
-                   }, 600);
-
-      }
-
-      // let's start
-      Scheduler(0);
-
-    </script>
-  </body>
-</html>