Bug 1531532: Remove incorrect reftest fuzzy annotation. r=bustage

layout/reftests/backgrounds/reftest.list

@@ -186,5 +186,4 @@ fuzzy-if(winWidget,0-102,0-2032) fuzzy-if(skiaContent,0-102,0-2811) fuzzy-if(web
 
 random-if(/^Windows\x20NT\x206\.1/.test(http.oscpu)) == background-clip-text-2.html background-clip-text-2-ref.html # Bug 1392106
 
-# this is unexplicably fuzzy on linux. the red background also shows up as rgb(252,13,27) for some reason
-fuzzy-if(webrender&&gtkWidget,36-36,138-138) == background-clip-text-scale.html background-clip-text-scale-ref.html
+== background-clip-text-scale.html background-clip-text-scale-ref.html