Don't force mach after https://bugzilla.mozilla.org/show_bug.cgi?id=1496746

diff --git Makefile.in Makefile.in
index 407e373573fb..16b8bb162d39 100644
--- Makefile.in
+++ Makefile.in
@@ -55,15 +55,8 @@ $(RUNNABLE_TIERS) binaries:: CLOBBER $(BUILD_BACKEND_FILES)
 endif
 endif
 
-ifdef JS_STANDALONE
 .PHONY: CLOBBER
 CLOBBER:
-else
-CLOBBER: $(topsrcdir)/CLOBBER
-	@echo 'STOP!  The CLOBBER file has changed.'
-	@echo 'Please run the build through "mach build".'
-	@exit 1
-endif
 
 install_manifests := \
   $(addprefix dist/,branding include public private xpi-stage) \