diff --git a/layout/reftests/bugs/722923-1-ref.html b/layout/reftests/bugs/722923-1-ref.html
new file mode 100644
index 00000000000..3ad50b559d8
--- /dev/null
+++ b/layout/reftests/bugs/722923-1-ref.html
@@ -0,0 +1,18 @@
+<!DOCTYPE html> 
+<html class="reftest-wait">
+<body>
+<div id="d" style="opacity:0.9; position:absolute; top:100px; width:200px; height:200px; background:lime"></div>
+<script>
+var d = document.getElementById("d");
+
+function doTest() {
+  d.style.opacity = 0.8;
+  setTimeout(function() {
+    d.style.opacity = 0.5;
+    document.documentElement.removeAttribute("class");
+  }, 50);
+}
+window.addEventListener("MozReftestInvalidate", doTest, false);
+</script>
+</body>
+</html>
diff --git a/layout/reftests/bugs/722923-1.html b/layout/reftests/bugs/722923-1.html
new file mode 100644
index 00000000000..35f38b5889f
--- /dev/null
+++ b/layout/reftests/bugs/722923-1.html
@@ -0,0 +1,20 @@
+<!DOCTYPE html> 
+<html class="reftest-wait">
+<body>
+<div id="d" style="opacity:0.9; height:10px;">
+  <div style="position:absolute; top:100px; width:200px; height:200px; background:lime"></div>
+</div>
+<script>
+var d = document.getElementById("d");
+
+function doTest() {
+  d.style.opacity = 0.8;
+  setTimeout(function() {
+    d.style.opacity = 0.5;
+    document.documentElement.removeAttribute("class");
+  }, 50);
+}
+window.addEventListener("MozReftestInvalidate", doTest, false);
+</script>
+</body>
+</html>
diff --git a/layout/reftests/bugs/reftest.list b/layout/reftests/bugs/reftest.list
index 5bd107a75ac..5868dcee87a 100644
--- a/layout/reftests/bugs/reftest.list
+++ b/layout/reftests/bugs/reftest.list
@@ -1690,3 +1690,4 @@ needs-focus != 703186-1.html 703186-2.html
 == 714519-2-q.html 714519-2-ref.html
 fuzzy-if(cocoaWidget,1,170) == 718521.html 718521-ref.html
 == 720987.html 720987-ref.html
+== 722923-1.html 722923-1-ref.html
