Bug 1332274 - Disable unstable requestIdleCallback test, a=testonly

MozReview-Commit-ID: N58VJEqZVu

testing/web-platform/meta/html/webappapis/idle-callbacks/callback-timeout-with-raf.html.ini

@@ -1,5 +1,6 @@
 [callback-timeout-with-raf.html]
   type: testharness
+  disabled: https://bugzilla.mozilla.org/show_bug.cgi?id=1332274
   [requestIdleCallback not scheduled when event loop is busy.]
     expected:
       if debug and e10s and (os == "win") and (version == "6.2.9200") and (processor == "x86_64") and (bits == 64): FAIL