cmd/compile/internal/syntax: print position info for names in tree dump
cmd/compile/internal/syntax: print position info for names in tree dump

Debugging support.

Change-Id: Ia518aaed36eaba76e6233306f718ad8aff3ce744
Reviewed-on: https://go-review.googlesource.com/37875
Reviewed-by: Matthew Dempsky <e56ac2c500064424afac424d4b5e53bd0570a731@google.com>

CAFxX/go,polyverse-security/go,CAFxX/go,codestation/go,linux-on-ibm-z/go,polyverse-security/go,josharian/go,CAFxX/go,Cofyc/go,josharian/go,golang/go,derekmarcotte/go,cloudflare/go,linux-on-ibm-z/go,Cofyc/go,polyverse-security/go,nawawi/go,golang/go,vsekhar/elastic-go,nawawi/go,Cofyc/go,derekmarcotte/go,codestation/go,golang/go,akutz/go,cloudflare/go,vsekhar/elastic-go,polyverse-security/go,vsekhar/elastic-go,polyverse-security/go,golang/go,Cofyc/go,nawawi/go,linux-on-ibm-z/go,josharian/go,CAFxX/go,polyverse-security/go,ImJasonH/go,akutz/go,derekmarcotte/go,CAFxX/go,nawawi/go,codestation/go,akutz/go,christopher-henderson/Go,golang/go,vsekhar/elastic-go,cloudflare/go,codestation/go,Cofyc/go,cloudflare/go,josharian/go,golang/go,ImJasonH/go,nawawi/go,linux-on-ibm-z/go,josharian/go,linux-on-ibm-z/go,josharian/go,cloudflare/go,akutz/go,golang/go,polyverse-security/go,cloudflare/go,vsekhar/elastic-go,ImJasonH/go,vsekhar/elastic-go,linux-on-ibm-z/go,vsekhar/elastic-go,ImJasonH/go,josharian/go,CAFxX/go,derekmarcotte/go,akutz/go,Cofyc/go,cloudflare/go,CAFxX/go,ImJasonH/go,linux-on-ibm-z/go,codestation/go,golang/go,derekmarcotte/go,codestation/go,ImJasonH/go,linux-on-ibm-z/go,derekmarcotte/go,derekmarcotte/go,codestation/go,akutz/go,nawawi/go,akutz/go,Cofyc/go,CAFxX/go,derekmarcotte/go,polyverse-security/go,nawawi/go,nawawi/go,ImJasonH/go,akutz/go,josharian/go,Cofyc/go,cloudflare/go,codestation/go,ImJasonH/go,vsekhar/elastic-go