Bug 1377188, part 3 - Mark WPT's the-hr-element-0/width.html test as passing on Mac. r=orange CLOSEDTREE

MozReview-Commit-ID: FrCoUEt7J0N

testing/web-platform/meta/html/rendering/non-replaced-elements/the-hr-element-0/width.html.ini

@@ -1,4 +1,4 @@
 [width.html]
   type: reftest
   expected:
-    if (os == "mac") or (os == "win"): FAIL
+    if (os == "win"): FAIL