The parenthesized flag guarantees that the contents was validated as a possible
arrow head. By collapsing a parenthesized expression with an outer binary
expression we invalidly kept the flag and invalidly assumed that the collapsed
expression was validated.

Bug: chromium:921382
Change-Id: I207dcbfd228a1ed216130226fdb7ea045b89b85a
Reviewed-on: https://chromium-review.googlesource.com/c/1412172
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58829}