This reverts commit 40d66d8b.

Reason for revert:
https://build.chromium.org/p/client.v8/builders/V8%20Mac64/builds/20910

Original change's description:
> [build] Make separate snapshot for trusted variant
> 
> This enables side-by-side snapshots with and without untrusted-code
> mitigations. It'll be the default in all V8 stand-alone builds
> with external startup data. Internal snapshots are not supported.
> 
> The files snapshot_blob.bin and snapshot_blob_trusted.bin will be
> bundled with V8 on swarming and the correct file is loaded dependent
> on the --untrusted-code-mitigations runtime flag.
> 
> Likewise we embed two snapshots for builtins.
> 
> Side-by-side snapshots won't be supported in Chromium.
> 
> Bug: v8:7441
> Change-Id: I2949ddfd5773649946b1c8e74751d48ad1d9c524
> Reviewed-on: https://chromium-review.googlesource.com/960004
> Commit-Queue: Michael Achenbach <machenbach@chromium.org>
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#52028}

TBR=rmcilroy@chromium.org,machenbach@chromium.org,yangguo@chromium.org,mstarzinger@chromium.org,jgruber@chromium.org

Change-Id: I5b18f7aff7c05a17842fc68d785bb617eeca4a41
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:7441
Reviewed-on: https://chromium-review.googlesource.com/968622Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52029}