This reverts commit 8ee7a97651.
Reason for revert: lld optimization level -Wl,-O1 appears to either
have a regression or to confuse Golem binary comparison tool.
Original change's description:
> [infra] Roll clang toolchain forward
>
> Change-Id: I41afe48f2fdc056436b58dc8158c62e9207cc43f
> Reviewed-on: https://dart-review.googlesource.com/32140
> Commit-Queue: Zach Anderson <zra@google.com>
> Reviewed-by: Alexander Thomas <athom@google.com>
TBR=whesse@google.com,rmacnak@google.com,zra@google.com,athom@google.com
# Not skipping CQ checks because original CL landed > 1 day ago.
Change-Id: I36ec03150a22f89c4cb5371dd1bf43df8a6f16f6
Reviewed-on: https://dart-review.googlesource.com/32800
Commit-Queue: Zach Anderson <zra@google.com>
Reviewed-by: Zach Anderson <zra@google.com>