--- a/dom/base/test/test_intersectionobservers.html
+++ b/dom/base/test/test_intersectionobservers.html
@@ -51,31 +51,26 @@ limitations under the License.
   function it(msg, fn) {
     tests.push({
       msg: `${msg} [${curDescribeMsg}]`,
       fn: fn
     });
   }
 
   var callbacks = [];
-  function callDelayed(fn, delay) {
-    callbacks.push({
-      fn: fn,
-      time: +new Date() + delay
-    });
+  function callDelayed(fn) {
+    callbacks.push(fn);
   }
 
   requestAnimationFrame(function tick() {
     var i = callbacks.length;
     while (i--) {
       var cb = callbacks[i];
-      if (+new Date() >= cb.time) {
-        SimpleTest.executeSoon(cb.fn);
-        callbacks.splice(i, 1);
-      }
+      SimpleTest.executeSoon(function() { SimpleTest.executeSoon(cb) });
+      callbacks.splice(i, 1);
     }
     requestAnimationFrame(tick);
   });
 
   function expect(val) {
     return {
       to: {
         throwException: function (regexp) {
@@ -328,32 +323,32 @@ limitations under the License.
         var spy = sinon.spy();
         io = new IntersectionObserver(spy, {root: rootEl});
 
         targetEl2.style.top = '-40px';
         io.observe(targetEl2);
         callDelayed(function() {
           expect(spy.callCount).to.be(1);
           done();
-        }, ASYNC_TIMEOUT);
+        });
       });
 
 
       it('does not trigger if target is not a descendant of the intersection root in the containing block chain',
           function(done) {
 
         var spy = sinon.spy();
         io = new IntersectionObserver(spy, {root: parentEl});
 
         parentEl.style.position = 'static';
         io.observe(targetEl2);
         callDelayed(function() {
           expect(spy.callCount).to.be(0);
           done();
-        }, ASYNC_TIMEOUT);
+        });
       });
 
       it('triggers if target or root becomes invisible',
           function(done) {
 
         var spy = sinon.spy();
         io = new IntersectionObserver(spy, {root: rootEl});
 
@@ -480,17 +475,17 @@ limitations under the License.
               done();
             });
           },
           function(done) {
             targetEl1.style.left = '-25px';
             callDelayed(function() {
               expect(spy.callCount).to.be(2);
               done();
-            }, ASYNC_TIMEOUT);
+            });
           },
           function(done) {
             targetEl1.style.left = '-10px';
             spy.waitForNotification(function() {
               expect(spy.callCount).to.be(3);
               var records = sortRecords(spy.lastCall.args[0]);
               expect(records.length).to.be(1);
               expect(records[0].intersectionRatio).to.be(0.5);
@@ -804,24 +799,24 @@ limitations under the License.
         targetEl1.remove();
 
         var spy = sinon.spy();
         io = new IntersectionObserver(spy, {root: rootEl});
 
         runSequence([
           function(done) {
             io.observe(targetEl1);
-            callDelayed(done, 0);
+            callDelayed(done);
           },
           function(done) {
             document.getElementById('fixtures').appendChild(rootEl);
             callDelayed(function() {
               expect(spy.callCount).to.be(1);
               done();
-            }, ASYNC_TIMEOUT);
+            });
           },
           function(done) {
             parentEl.insertBefore(targetEl1, targetEl2);
             spy.waitForNotification(function() {
               expect(spy.callCount).to.be(2);
               var records = sortRecords(spy.lastCall.args[0]);
               expect(records.length).to.be(1);
               expect(records[0].intersectionRatio).to.be(1);
@@ -871,17 +866,17 @@ limitations under the License.
           expect(records.length).to.be(1);
           expect(records[0].intersectionRatio).to.be(1);
           done();
         }, {root: rootEl});
 
         io.observe(targetEl3);
         callDelayed(function() {
           parentEl.scrollLeft = 40;
-        }, 0);
+        });
       });
 
 
       it('supports CSS transitions and transforms', function(done) {
 
         targetEl1.style.top = '220px';
         targetEl1.style.left = '220px';
 
@@ -895,17 +890,17 @@ limitations under the License.
           expect(records.length).to.be(1);
           expect(records[0].intersectionRatio).to.be(1);
           done();
         }, {root: rootEl, threshold: [1]});
 
         io.observe(targetEl1);
         callDelayed(function() {
           targetEl1.style.transform = 'translateX(-40px) translateY(-40px)';
-        }, 0);
+        });
       });
 
 
       it('uses the viewport when no root is specified', function(done) {
         window.onmessage = function (e) {
           expect(e.data).to.be.ok();
           win.close();
           done();
@@ -920,17 +915,17 @@ limitations under the License.
         io.observe(targetEl1);
         io.observe(targetEl1);
         io.observe(targetEl1);
 
         spy.waitForNotification(function() {
           callDelayed(function () {
             expect(spy.callCount).to.be(1);
             done();
-          }, ASYNC_TIMEOUT);
+          });
         });
       });
 
     });
 
     describe('observe subframe', function () {
       
       it('should not trigger if target and root are not in the same document',
@@ -940,17 +935,17 @@ limitations under the License.
         io = new IntersectionObserver(spy, {root: rootEl});
 
         targetEl4.onload = function () {
           targetEl5 = targetEl4.contentDocument.getElementById('target5');
           io.observe(targetEl5);
           callDelayed(function() {
             expect(spy.callCount).to.be(0);
             done();
-          }, ASYNC_TIMEOUT);
+          });
         }
 
         targetEl4.src = "intersectionobserver_iframe.html";
       
       });
 
       it('boundingClientRect matches target.getBoundingClientRect() for an element inside an iframe',
           function(done) {
@@ -1000,17 +995,17 @@ limitations under the License.
           if (!lastestRecords.length) {
             requestAnimationFrame(wait);
             return;
           }
           callDelayed(function() {
             expect(lastestRecords.length).to.be(1);
             expect(lastestRecords[0].intersectionRatio).to.be(1);
             done();
-          }, ASYNC_TIMEOUT);
+          });
         });
         
       });
 
     });
 
     describe('unobserve', function() {
 
@@ -1051,17 +1046,17 @@ limitations under the License.
           },
           function(done) {
             io.unobserve(targetEl2);
             targetEl1.style.top = targetEl2.style.top = '0px';
             targetEl1.style.left = targetEl2.style.left = '0px';
             callDelayed(function() {
               expect(spy.callCount).to.be(2);
               done();
-            }, ASYNC_TIMEOUT);
+            });
           }
         ], done);
 
       });
 
     });
 
     describe('disconnect', function() {
@@ -1090,17 +1085,17 @@ limitations under the License.
           },
           function(done) {
             io.disconnect();
             targetEl1.style.top = targetEl2.style.top = '0px';
             targetEl1.style.left = targetEl2.style.left = '-40px';
             callDelayed(function() {
               expect(spy.callCount).to.be(1);
               done();
-            }, ASYNC_TIMEOUT);
+            });
           }
         ], done);
 
       });
 
     });
 
   });