--- a/layout/style/test/chrome/test_display_mode.html
+++ b/layout/style/test/chrome/test_display_mode.html
@@ -59,27 +59,27 @@ add_task(async function() {
 
   shouldApply("all and (display-mode: browser)");
   shouldNotApply("all and (display-mode: fullscreen)");
   shouldNotApply("all and (display-mode: standalone)");
   shouldNotApply("all and (display-mode: minimal-ui)");
 
   // Test entering the OS's fullscreen mode.
   var fullScreenEntered = waitOneEvent(win, "sizemodechange");
-  await promiseNextTick();
   synthesizeKey("VK_F11", {});
   await fullScreenEntered;
+  // Wait for the next tick to apply media feature changes. See bug 1430380.
+  await promiseNextTick();
   shouldApply("all and (display-mode: fullscreen)");
   shouldNotApply("all and (display-mode: browser)");
   var fullScreenExited = waitOneEvent(win, "sizemodechange");
-  // Need to wait for the next tick to to avoid nested fullscreen change
-  // in different direction. See bug 1415781.
-  await promiseNextTick();
   synthesizeKey("VK_F11", {});
   await fullScreenExited;
+  // Wait for the next tick to apply media feature changes. See bug 1430380.
+  await promiseNextTick();
   shouldNotApply("all and (display-mode: fullscreen)");
   shouldApply("all and (display-mode: browser)");
 
   // Test entering fullscreen through document requestFullScreen.
   fullScreenEntered = waitOneEvent(document, "mozfullscreenchange");
   document.body.mozRequestFullScreen();
   await fullScreenEntered
   ok(document.mozFullScreenElement, "window entered fullscreen");

--- a/layout/style/test/chrome/test_display_mode_reflow.html
+++ b/layout/style/test/chrome/test_display_mode_reflow.html
@@ -38,26 +38,28 @@ add_task(async function() {
   var bodyComputedStyled = subdoc.defaultView.getComputedStyle(subdoc.body);
   var win = Services.wm.getMostRecentWindow("navigator:browser");
 
   var secondDiv = subdoc.getElementById("b");
   var offsetTop = secondDiv.offsetTop;
 
   // Test entering the OS's fullscreen mode.
   var fullScreenEntered = waitOneEvent(win, "sizemodechange");
-  await promiseNextTick();
   synthesizeKey("VK_F11", {});
   await fullScreenEntered;
+
+  // Wait for the next tick to apply media feature changes. See bug 1430380.
+  await promiseNextTick();
   ok(offsetTop !== secondDiv.offsetTop, "offset top changes");
   var fullScreenExited = waitOneEvent(win, "sizemodechange");
-  // Need to wait for the next tick to to avoid nested fullscreen change
-  // in different direction. See bug 1415781.
-  await promiseNextTick();
   synthesizeKey("VK_F11", {});
   await fullScreenExited;
+
+  // Wait for the next tick to apply media feature changes. See bug 1430380.
+  await promiseNextTick();
   ok(offsetTop === secondDiv.offsetTop, "offset top returns to original value");
 
   offsetTop = secondDiv.offsetTop;
   // Test entering fullscreen through document requestFullScreen.
   fullScreenEntered = waitOneEvent(document, "mozfullscreenchange");
   document.body.mozRequestFullScreen();
   await fullScreenEntered
   ok(offsetTop !== secondDiv.offsetTop, "offset top changes");