Bug 579885. Fix test.

layout/reftests/bugs/579985-1.html

@@ -4,7 +4,7 @@
 <script>
 function doTest() {
   var d = document.getElementById("d");
-  d.style.opacity = 0.75;
+  d.style.opacity = 0.5;
   document.documentElement.removeAttribute("class");
 }
 window.addEventListener("MozReftestInvalidate", doTest, false);

layout/reftests/bugs/reftest.list

@@ -1507,7 +1507,7 @@ random-if(layersGPUAccelerated) == 564991-1.html 564991-1-ref.html
 == 577838-2.html 577838-2-ref.html
 random-if(layersGPUAccelerated) == 579323-1.html 579323-1-ref.html
 == 579349-1.html 579349-1-ref.html
-# == 579985-1.html 579985-1-ref.html
+random-if(layersGPUAccelerated) == 579985-1.html 579985-1-ref.html # this bug was only for a regression in BasicLayers anyway
 == 580160-1.html 580160-1-ref.html
 HTTP(..) == 580863-1.html 580863-1-ref.html
 random-if(layersGPUAccelerated) == 581317-1.html 581317-1-ref.html