Test nil check removal for access of PAUTOHEAP. Change-Id: Id739a9cda7cd3ff173bdcccfedcad93ee90711ef Reviewed-on: https://go-review.googlesource.com/27232 Run-TryBot: Cherry Zhang <cherryyz@google.com> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org>