Bug 891993: Mark toolkit/components/downloads/ as FAIL_ON_WARNINGS. r=mak

toolkit/components/downloads/Makefile.in

@@ -13,6 +13,7 @@ include $(DEPTH)/config/autoconf.mk
 LIBRARY_NAME = download_s
 FORCE_STATIC_LIB = 1
 LIBXUL_LIBRARY = 1
+FAIL_ON_WARNINGS = 1
 
 # definition of MOZ_SUITE is only added via config.mk
 include $(topsrcdir)/config/config.mk