Revert "[infra] Remove copy of jsshell to legacy location"
Revert "[infra] Remove copy of jsshell to legacy location"

This reverts commit 27d3969eaedda668ac92a052469a9d7f0c92cff2.

Reason for revert: 
The benchmark-linux-try bot started failing after this CL landed, see:

https://ci.chromium.org/ui/p/dart/builders/try/benchmark-linux-try/57377/overview

https://ci.chromium.org/ui/p/dart/builders/try/benchmark-linux-try/57390/overview

Likely there is still a dependency on the legacy location that needs to be cleaned up.

Original change's description:
> [infra] Remove copy of jsshell to legacy location
>
> Fixes: b/186078239
> Change-Id: I963af391e67734b9dc130258a871f9b0a2966858
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/214047
> Reviewed-by: Alexander Thomas <athom@google.com>

TBR=whesse@google.com,athom@google.com

Change-Id: I89702406796286c8fef5def0f88364c5b6709ca1
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/227360
Reviewed-by: Sigmund Cherem <beaea8fd7d2a56555046ba4f362c8a93e3938576@google.com>
Commit-Queue: Sigmund Cherem <beaea8fd7d2a56555046ba4f362c8a93e3938576@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk