CL 419456 starts using lookupObj to find types2.Object associated with
builtin functions. However, the new code does not un-parenthesized the
callee expression, causing an ICE because of nil obj returned.
Un-parenthesizing the callee expression fixes the problem.
Fixes#63436
Change-Id: Iebb4fbc08575e7d0b1dbd026c98e8f949ca16460
Reviewed-on: https://go-review.googlesource.com/c/go/+/533476
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Keith Randall <khr@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
