--- a/layout/reftests/bugs/reftest.list
+++ b/layout/reftests/bugs/reftest.list
@@ -1856,17 +1856,17 @@ test-pref(layout.css.grid.enabled,true) 
 == 1059498-1.html 1059498-1-ref.html
 == 1059498-2.html 1059498-1-ref.html
 == 1059498-3.html 1059498-1-ref.html
 == 1062108-1.html 1062108-1-ref.html
 == 1062792-1.html 1062792-1-ref.html
 == 1062963-floatmanager-reflow.html 1062963-floatmanager-reflow-ref.html
 test-pref(dom.webcomponents.enabled,true) == 1066554-1.html 1066554-1-ref.html
 == 1069716-1.html 1069716-1-ref.html
-fails-if(webrender) == 1078262-1.html about:blank
+random-if(webrender) == 1078262-1.html about:blank
 test-pref(layout.testing.overlay-scrollbars.always-visible,false) == 1081072-1.html 1081072-1-ref.html
 == 1081185-1.html 1081185-1-ref.html
 == 1097437-1.html 1097437-1-ref.html
 == 1103258-1.html 1103258-1-ref.html # assertion crash test with layers culling test
 == 1105137-1.html 1105137-1-ref.html
 fuzzy-if(d2d,36,304) fuzzy-if(/^Windows\x20NT\x2010\.0/.test(http.oscpu)&&d2d,127,701) == 1116480-1-fakeitalic-overflow.html 1116480-1-fakeitalic-overflow-ref.html
 == 1111753-1.html about:blank
 == 1114526-1.html 1114526-1-ref.html

--- a/layout/reftests/css-animations/reftest.list
+++ b/layout/reftests/css-animations/reftest.list
@@ -15,20 +15,20 @@ test-pref(layers.offmainthreadcompositio
 # We need to run transform:none test case when OMTA is disabled to check that the animation creates a stacking context even if the animation is not running on the compositor
 test-pref(layers.offmainthreadcomposition.async-animations,false) == stacking-context-transform-none-animation.html stacking-context-animation-ref.html
 == no-stacking-context-opacity-removing-animation-in-delay.html no-stacking-context-animation-ref.html
 == no-stacking-context-transform-removing-animation-in-delay.html no-stacking-context-animation-ref.html
 == stacking-context-lose-opacity-1.html stacking-context-animation-ref.html
 == stacking-context-lose-transform-none.html stacking-context-animation-ref.html
 == stacking-context-opacity-win-in-delay.html stacking-context-animation-ref.html
 == stacking-context-opacity-win-in-delay-on-main-thread.html stacking-context-animation-ref.html
-== stacking-context-opacity-wins-over-transition.html stacking-context-animation-ref.html
+fails-if(webrender) == stacking-context-opacity-wins-over-transition.html stacking-context-animation-ref.html
 == stacking-context-transform-win-in-delay.html stacking-context-animation-ref.html
 == stacking-context-transform-win-in-delay-on-main-thread.html stacking-context-animation-ref.html
-== stacking-context-transform-wins-over-transition.html stacking-context-animation-ref.html
+fails-if(webrender) == stacking-context-transform-wins-over-transition.html stacking-context-animation-ref.html
 == stacking-context-opacity-1-animation.html stacking-context-animation-ref.html
 == stacking-context-opacity-1-with-fill-backwards.html stacking-context-animation-ref.html
 == stacking-context-opacity-1-with-fill-forwards.html stacking-context-animation-ref.html
 == stacking-context-paused-on-opacity-1.html stacking-context-animation-ref.html
 == stacking-context-paused-on-transform-none.html stacking-context-animation-ref.html
 == stacking-context-transform-none-animation.html stacking-context-animation-ref.html
 == stacking-context-transform-none-animation-on-svg.html  stacking-context-animation-ref.html
 == stacking-context-transform-none-animation-with-backface-visibility.html stacking-context-animation-ref.html
@@ -62,9 +62,9 @@ fails-if(layerChecksEnabled) == backgrou
 == change-animation-name-to-none-in-rule.html change-animation-name-in-rule-ref.html
 == change-animation-name-to-other-in-rule.html change-animation-name-in-rule-ref.html
 == change-animation-name-to-non-existent-in-rule.html change-animation-name-in-rule-ref.html
 == no-style-sharing-with-animations.html no-style-sharing-with-animations-ref.html
 
 == continuation-opacity.html continuation-opacity-ref.html
 == ib-split-sibling-opacity.html about:blank
 
-== opacity-animation-in-fixed-opacity-parent.html opacity-animation-in-fixed-opacity-parent-ref.html
+skip-if(webrender) == opacity-animation-in-fixed-opacity-parent.html opacity-animation-in-fixed-opacity-parent-ref.html

--- a/layout/reftests/css-transitions/reftest.list
+++ b/layout/reftests/css-transitions/reftest.list
@@ -1,11 +1,11 @@
 == transitions-inline-already-wrapped-1.html transitions-inline-ref.html
 == transitions-inline-already-wrapped-2.html transitions-inline-ref.html
 == transitions-inline-rewrap-1.html transitions-inline-ref.html
 == transitions-inline-rewrap-2.html transitions-inline-ref.html
 == stacking-context-opacity-lose-to-animation.html stacking-context-transition-ref.html
 == stacking-context-transform-lose-to-animation.html stacking-context-transition-ref.html
-== stacking-context-opacity-wins-over-important-style.html stacking-context-transition-ref.html
-== stacking-context-transform-wins-over-important-style.html stacking-context-transition-ref.html
+fails-if(webrender) == stacking-context-opacity-wins-over-important-style.html stacking-context-transition-ref.html
+fails-if(webrender) == stacking-context-transform-wins-over-important-style.html stacking-context-transition-ref.html
 == transition-and-animation-with-different-durations.html transition-and-animation-with-different-durations-ref.html
 == reframe-and-transition-starts-at-the-same-time.html reframe-and-transition-starts-at-the-same-time-ref.html
 == style-change-during-transition.html style-change-during-transition-ref.html

--- a/layout/reftests/web-animations/reftest.list
+++ b/layout/reftests/web-animations/reftest.list
@@ -1,24 +1,24 @@
 test-pref(dom.animations-api.core.enabled,true) == 1246046-1.html green-box.html
 test-pref(dom.animations-api.core.enabled,true) == 1267937-1.html 1267937-ref.html
 test-pref(dom.animations-api.core.enabled,true) == 1298742-1.html 1298742-ref.html
 test-pref(dom.animations-api.core.enabled,true) == 1363639-1.html green-box.html
-test-pref(dom.animations-api.core.enabled,true) == stacking-context-transform-none-animation-before-appending-element.html stacking-context-animation-ref.html
-test-pref(dom.animations-api.core.enabled,true) == stacking-context-opacity-changing-keyframe.html stacking-context-animation-ref.html
+test-pref(dom.animations-api.core.enabled,true) random-if(webrender) == stacking-context-transform-none-animation-before-appending-element.html stacking-context-animation-ref.html
+test-pref(dom.animations-api.core.enabled,true) random-if(webrender) == stacking-context-opacity-changing-keyframe.html stacking-context-animation-ref.html
 test-pref(dom.animations-api.core.enabled,true) == stacking-context-opacity-changing-keyframe-in-delay.html stacking-context-animation-ref.html
-test-pref(dom.animations-api.core.enabled,true) == stacking-context-opacity-changing-target.html stacking-context-animation-changing-target-ref.html
+test-pref(dom.animations-api.core.enabled,true) random-if(webrender) == stacking-context-opacity-changing-target.html stacking-context-animation-changing-target-ref.html
 test-pref(dom.animations-api.core.enabled,true) == stacking-context-opacity-changing-target-in-delay.html stacking-context-animation-changing-target-ref.html
-test-pref(dom.animations-api.core.enabled,true) == stacking-context-opacity-changing-effect.html stacking-context-animation-ref.html
+test-pref(dom.animations-api.core.enabled,true) random-if(webrender) == stacking-context-opacity-changing-effect.html stacking-context-animation-ref.html
 test-pref(dom.animations-api.core.enabled,true) == stacking-context-opacity-losing-css-animation-in-delay.html stacking-context-animation-ref.html
-test-pref(dom.animations-api.core.enabled,true) == stacking-context-transform-changing-keyframe.html stacking-context-animation-ref.html
+test-pref(dom.animations-api.core.enabled,true) random-if(webrender) == stacking-context-transform-changing-keyframe.html stacking-context-animation-ref.html
 test-pref(dom.animations-api.core.enabled,true) == stacking-context-transform-changing-keyframe-in-delay.html stacking-context-animation-ref.html
-test-pref(dom.animations-api.core.enabled,true) == stacking-context-transform-changing-target.html stacking-context-animation-changing-target-ref.html
+test-pref(dom.animations-api.core.enabled,true) random-if(webrender) == stacking-context-transform-changing-target.html stacking-context-animation-changing-target-ref.html
 
 test-pref(dom.animations-api.core.enabled,true) == stacking-context-transform-changing-target-in-delay.html stacking-context-animation-changing-target-ref.html
-test-pref(dom.animations-api.core.enabled,true) == stacking-context-transform-changing-effect.html stacking-context-animation-ref.html
-test-pref(dom.animations-api.core.enabled,true) == stacking-context-transform-changing-display-property.html stacking-context-animation-ref.html
+test-pref(dom.animations-api.core.enabled,true) random-if(webrender) == stacking-context-transform-changing-effect.html stacking-context-animation-ref.html
+test-pref(dom.animations-api.core.enabled,true) random-if(webrender) == stacking-context-transform-changing-display-property.html stacking-context-animation-ref.html
 test-pref(dom.animations-api.core.enabled,true) == stacking-context-transform-losing-css-animation-in-delay.html stacking-context-animation-ref.html
 test-pref(dom.animations-api.core.enabled,true) == style-updates-on-iteration-composition-changed-from-accumulate-to-replace.html style-updates-for-iteration-composite-ref.html
 test-pref(dom.animations-api.core.enabled,true) == style-updates-on-iteration-composition-changed-from-replace-to-accumulate.html style-updates-for-iteration-composite-ref.html
 test-pref(dom.animations-api.core.enabled,true) == style-updates-on-current-iteration-changed.html style-updates-for-iteration-composite-ref.html
 test-pref(dom.animations-api.core.enabled,true) == cancel-animation-with-selector-matching.html about:blank
 test-pref(dom.animations-api.core.enabled,true) == child-in-animating-element-display-none.html child-in-animating-element-display-none-ref.html