Bug 1447480 - Add support of MOZ_FALLTHROUGH_ASSERT without any argument r=hsivonen

MozReview-Commit-ID: 6xrdrggcVFR

--HG--
extra : rebase_source : f53d9a62e828d65469c42c79a468b5bea2e8b645

mfbt/Assertions.h

@@ -596,7 +596,7 @@ struct AssertionConditionType
  * }
  */
 #ifdef DEBUG
-#  define MOZ_FALLTHROUGH_ASSERT(reason) MOZ_CRASH("MOZ_FALLTHROUGH_ASSERT: " reason)
+#  define MOZ_FALLTHROUGH_ASSERT(...) MOZ_CRASH("MOZ_FALLTHROUGH_ASSERT: " __VA_ARGS__)
 #else
 #  define MOZ_FALLTHROUGH_ASSERT(...) MOZ_FALLTHROUGH
 #endif