diff --git a/gfx/layers/apz/test/mochitest/apz_test_utils.js b/gfx/layers/apz/test/mochitest/apz_test_utils.js
index b6a07c6adedf..9cbf95aeb278 100644
--- a/gfx/layers/apz/test/mochitest/apz_test_utils.js
+++ b/gfx/layers/apz/test/mochitest/apz_test_utils.js
@@ -209,6 +209,10 @@ function runSubtestsSeriallyInFreshWindows(aSubtests) {
   });
 }
 
+function pushPrefs(prefs) {
+  return SpecialPowers.pushPrefEnv({'set': prefs});
+}
+
 function waitUntilApzStable() {
   return new Promise(function(resolve, reject) {
     SimpleTest.waitForFocus(function() {
diff --git a/gfx/layers/apz/test/mochitest/test_layerization.html b/gfx/layers/apz/test/mochitest/test_layerization.html
index 1ba093f1ec61..e85d6fdcfcdd 100644
--- a/gfx/layers/apz/test/mochitest/test_layerization.html
+++ b/gfx/layers/apz/test/mochitest/test_layerization.html
@@ -229,9 +229,7 @@ function startTest() {
     return;
   }
 
-  waitForAllPaints(function() {
-    flushApzRepaints(driveTest);
-  })
+  driveTest();
 }
 
 SimpleTest.waitForExplicitFinish();
@@ -243,12 +241,12 @@ SimpleTest.expectAssertions(0, 8); // we get a bunch of "ASSERTION: Bounds compu
 // wheel event as corresponding to a later wheel event.
 // Also enable APZ test logging, since we use that data to determine whether
 // a scroll frame was layerized.
-SpecialPowers.pushPrefEnv({"set": [["general.smoothScroll", false],
-                                   ["apz.displayport_expiry_ms", 0],
-                                   ["apz.test.logging_enabled", true]]},
-                          function() {
-                            SimpleTest.waitForFocus(startTest, window);
-                          });
+pushPrefs([["general.smoothScroll", false],
+           ["apz.displayport_expiry_ms", 0],
+           ["apz.test.logging_enabled", true]])
+.then(waitUntilApzStable)
+.then(startTest);
+
 </script>
 </pre>
 </body>
diff --git a/gfx/layers/apz/test/mochitest/test_scroll_inactive_bug1190112.html b/gfx/layers/apz/test/mochitest/test_scroll_inactive_bug1190112.html
index 0868ffe73379..3349ef1abc7c 100644
--- a/gfx/layers/apz/test/mochitest/test_scroll_inactive_bug1190112.html
+++ b/gfx/layers/apz/test/mochitest/test_scroll_inactive_bug1190112.html
@@ -2,9 +2,10 @@
 <html>
 <head>
   <title>Test scrolling flattened inactive frames</title>
-  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
   <script type="application/javascript" src="/tests/SimpleTest/EventUtils.js"></script>
   <script type="application/javascript" src="/tests/SimpleTest/paint_listener.js"></script>
+  <script type="application/javascript" src="apz_test_utils.js"></script>
   <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
 <style>
 p {
@@ -526,18 +527,15 @@ function doInnerScrollAgain(subframe, oldpos) {
   });
 }
 
-window.onload = function() {
-  SpecialPowers.pushPrefEnv({
-    'set': [['general.smoothScroll', false],
-            ['mousewheel.transaction.timeout', 0],
-            ['mousewheel.transaction.ignoremovedelay', 0]]
-  }, function () {
-    SimpleTest.waitForFocus(test);
-  });
-}
-
 SimpleTest.testInChaosMode();
 SimpleTest.waitForExplicitFinish();
+
+pushPrefs([['general.smoothScroll', false],
+           ['mousewheel.transaction.timeout', 0],
+           ['mousewheel.transaction.ignoremovedelay', 0]])
+.then(waitUntilApzStable)
+.then(test);
+
 </script>
 </body>
 </html>
diff --git a/gfx/layers/apz/test/mochitest/test_scroll_inactive_flattened_frame.html b/gfx/layers/apz/test/mochitest/test_scroll_inactive_flattened_frame.html
index e82b2252fbbe..51e16aab977a 100644
--- a/gfx/layers/apz/test/mochitest/test_scroll_inactive_flattened_frame.html
+++ b/gfx/layers/apz/test/mochitest/test_scroll_inactive_flattened_frame.html
@@ -36,23 +36,14 @@ function test() {
   });
 }
 
-function startTest() {
-  waitForAllPaints(function() {
-    flushApzRepaints(test);
-  });
-}
-
-window.onload = function() {
-  SpecialPowers.pushPrefEnv({
-    'set': [['general.smoothScroll', false],
-            ['mousewheel.transaction.timeout', 1000000]],
-  }, function () {
-    SimpleTest.waitForFocus(startTest);
-  });
-}
-
 SimpleTest.testInChaosMode();
 SimpleTest.waitForExplicitFinish();
+
+pushPrefs([['general.smoothScroll', false],
+           ['mousewheel.transaction.timeout', 1000000]])
+.then(waitUntilApzStable)
+.then(test);
+
 </script>
 </body>
 </html>
diff --git a/gfx/layers/apz/test/mochitest/test_scroll_subframe_scrollbar.html b/gfx/layers/apz/test/mochitest/test_scroll_subframe_scrollbar.html
index db39787ffb19..4d9da8c2c0b4 100644
--- a/gfx/layers/apz/test/mochitest/test_scroll_subframe_scrollbar.html
+++ b/gfx/layers/apz/test/mochitest/test_scroll_subframe_scrollbar.html
@@ -104,23 +104,14 @@ function testScrolling(subframe) {
   });
 }
 
-function startTest() {
-  waitForAllPaints(function() {
-    flushApzRepaints(test);
-  });
-}
-
-window.onload = function() {
-  SpecialPowers.pushPrefEnv({
-    'set': [['general.smoothScroll', false],
-            ['mousewheel.transaction.timeout', 0],
-            ['mousewheel.transaction.ignoremovedelay', 0]]
-  }, function () {
-    SimpleTest.waitForFocus(startTest);
-  });
-}
-
 SimpleTest.waitForExplicitFinish();
+
+pushPrefs([['general.smoothScroll', false],
+           ['mousewheel.transaction.timeout', 0],
+           ['mousewheel.transaction.ignoremovedelay', 0]])
+.then(waitUntilApzStable)
+.then(test);
+
 </script>
 </body>
 </html>
diff --git a/gfx/layers/apz/test/mochitest/test_wheel_scroll.html b/gfx/layers/apz/test/mochitest/test_wheel_scroll.html
index 8fe8980bfeae..e7d949a7d29c 100644
--- a/gfx/layers/apz/test/mochitest/test_wheel_scroll.html
+++ b/gfx/layers/apz/test/mochitest/test_wheel_scroll.html
@@ -6,7 +6,9 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1013412
 <head>
   <title>Test for Bug 1013412</title>
   <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
-  <script type="text/javascript" src="/tests/SimpleTest/EventUtils.js"></script>
+  <script type="application/javascript" src="/tests/SimpleTest/EventUtils.js"></script>
+  <script type="application/javascript" src="/tests/SimpleTest/paint_listener.js"></script>
+  <script type="application/javascript" src="apz_test_utils.js"></script>
   <script type="application/javascript" src="apz_test_native_event_utils.js"></script>
   <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
   <style>
@@ -99,16 +101,15 @@ function continueTest() {
   }
 }
 
-function startTest() {
-  // If we allow smooth scrolling the "smooth" scrolling may cause the page to
-  // glide past the scrollbox (which is supposed to stop the scrolling) and so
-  // we might end up at the bottom of the page.
-  SpecialPowers.pushPrefEnv({"set": [["general.smoothScroll", false]]}, continueTest);
-}
-
 SimpleTest.testInChaosMode();
 SimpleTest.waitForExplicitFinish();
-SimpleTest.waitForFocus(startTest, window);
+
+// If we allow smooth scrolling the "smooth" scrolling may cause the page to
+// glide past the scrollbox (which is supposed to stop the scrolling) and so
+// we might end up at the bottom of the page.
+pushPrefs([["general.smoothScroll", false]])
+.then(waitUntilApzStable)
+.then(continueTest);
 
 </script>
 </pre>
diff --git a/gfx/layers/apz/test/mochitest/test_wheel_transactions.html b/gfx/layers/apz/test/mochitest/test_wheel_transactions.html
index 65f68d8239c7..37efbb9fdee8 100644
--- a/gfx/layers/apz/test/mochitest/test_wheel_transactions.html
+++ b/gfx/layers/apz/test/mochitest/test_wheel_transactions.html
@@ -132,20 +132,13 @@ function driveTest() {
   }
 }
 
-function startTest() {
-  waitForAllPaints(function() {
-    flushApzRepaints(driveTest);
-  });
-}
+SimpleTest.waitForExplicitFinish();
 
 // Disable smooth scrolling because it makes the test flaky (we don't have a good
 // way of detecting when the scrolling is finished).
-SpecialPowers.pushPrefEnv({"set": [["general.smoothScroll", false]]},
-                          function() {
-                            SimpleTest.waitForFocus(startTest, window);
-                          });
-
-SimpleTest.waitForExplicitFinish();
+pushPrefs([["general.smoothScroll", false]])
+.then(waitUntilApzStable)
+.then(driveTest);
 
 </script>
 </pre>
