This reverts commit 6c613288.

Reason for revert: breaks compilation on win64 bot: https://build.chromium.org/p/client.v8/builders/V8%20Win64%20-%20msvc/builds/69

Original change's description:
> [Liftoff] Implement parallel register moves
> 
> This was not implemented so far, leading to lots of clusterfuzz issues.
> Testing this feature would require complicating the interface a lot and
> exposing more implementation details in the header file, hence we just
> go with regression tests for now.
> 
> R=​ahaas@chromium.org, titzer@chromium.org
> 
> Bug: v8:6600, chromium:782280
> Change-Id: I12863f3eb59a8dffdcc7d3bfb8e1f0ae0eec15ee
> Reviewed-on: https://chromium-review.googlesource.com/758772
> Reviewed-by: Andreas Haas <ahaas@chromium.org>
> Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#49286}

TBR=titzer@chromium.org,ahaas@chromium.org,clemensh@chromium.org

Change-Id: I386983da7f9f03d54cef2190b01fd2cc5785966e
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:6600, chromium:782280
Reviewed-on: https://chromium-review.googlesource.com/763367Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49289}