cmd/compile/internal/types: remove Sym.Block and Sym.Lastlineno
These fields were used for tracking the last scope/position that an
identifier was declared, so that we could report redeclaration
errors. However, redeclaration errors are now diagnosed by types2 (and
typecheck.Redeclared was removed in CL 388537), so these fields can be
safely pruned.
Updates #51691.
Change-Id: Ifd5ea3f6795fadb420913298d59287c95e4669a1
Reviewed-on: https://go-review.googlesource.com/c/go/+/394276
Trust: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>