Bug 1340530 - stylo: Disable leaking test. r=heycam

MozReview-Commit-ID: 4MkNBwcAuf

--HG--
extra : rebase_source : 87a9dea9e67c96640060f7b832b728123cff6eaf

layout/reftests/w3c-css/submitted/values3/reftest-stylo.list

@@ -1,5 +1,5 @@
 # DO NOT EDIT! This is a auto-generated temporary list for Stylo testing
-== calc-background-linear-gradient-1.html calc-background-linear-gradient-1.html
+# == calc-background-linear-gradient-1.html calc-background-linear-gradient-1.html
 == calc-background-image-gradient-1.html calc-background-image-gradient-1.html
 == calc-background-position-1.html calc-background-position-1.html
 == calc-background-size-1.html calc-background-size-1.html