go.tools/go/types: introduce Func.Scope()
go.tools/go/types: introduce Func.Scope()

The goal is to allow clients to distinguish function-local objects
from package-local objects and identify the specific function by
examining its scope. For example, a compiler may need to mangle
object names according to the outer function name.

R=gri
CC=golang-codereviews, golang-dev
https://codereview.appspot.com/52280043

Committer: Robert Griesemer <a6752097faebf1f02d80107d77a9be009089afe3@golang.org>

t-yuki/go.tools.old,t-yuki/go.tools.old,t-yuki/go.tools.old