text/template: always return nil for (next Node)

[tnclong]

src/text/template/parse/parse.go:280:func (t *Tree) parse() (next Node)

The return value may don't necessary now.
Would mind any guy to have a check?

[ianlancetaylor]

Yes, looks like the return value has not been needed since https://golang.org/cl/5393049 .

[dmah42]

i'd like to take this (for a gentle introduction to making changes to golang).

[gopherbot]

CL https://golang.org/cl/27240 mentions this issue.