Bug 1447040 - Disable cache-abort serviceworker test on mac debug, a=testonly

MozReview-Commit-ID: AG1rleCpnmO

testing/web-platform/meta/service-workers/cache-storage/serviceworker/cache-abort.https.html.ini

@@ -1,4 +1,7 @@
 [cache-abort.https.html]
+  disabled:
+    if debug and os == "mac": bug 1447040
+
   [put() followed by abort after headers received should reject with AbortError]
     expected: FAIL