cmd/compile/internal/syntax: remove unused code
cmd/compile/internal/syntax: remove unused code

Change-Id: I9c75dee7e4498cc11c08cad1ae34ff2af75f1469
Reviewed-on: https://go-review.googlesource.com/69071
Reviewed-by: Matthew Dempsky <e56ac2c500064424afac424d4b5e53bd0570a731@google.com>

codestation/go,codestation/go,polyverse-security/go,golang/go,Cofyc/go,polyverse-security/go,polyverse-security/go,akutz/go,golang/go,josharian/go,codestation/go,christopher-henderson/Go,nawawi/go,polyverse-security/go,codestation/go,akutz/go,nawawi/go,josharian/go,josharian/go,cloudflare/go,Cofyc/go,golang/go,cloudflare/go,golang/go,cloudflare/go,Cofyc/go,CAFxX/go,josharian/go,CAFxX/go,CAFxX/go,golang/go,CAFxX/go,cloudflare/go,nawawi/go,josharian/go,Cofyc/go,akutz/go,cloudflare/go,codestation/go,CAFxX/go,akutz/go,polyverse-security/go,golang/go,golang/go,Cofyc/go,codestation/go,CAFxX/go,cloudflare/go,polyverse-security/go,josharian/go,Cofyc/go,nawawi/go,nawawi/go,polyverse-security/go,nawawi/go,CAFxX/go,josharian/go,golang/go,Cofyc/go,cloudflare/go,nawawi/go,codestation/go,akutz/go,nawawi/go,akutz/go,josharian/go,codestation/go,akutz/go,akutz/go,Cofyc/go,CAFxX/go,cloudflare/go,polyverse-security/go