This reverts commit e7f9fb4a.

Reason for revert: msvc compile error: https://build.chromium.org/p/client.v8/builders/V8%20Win64%20-%20msvc/builds/1573

Original change's description:
> [Assembler][x64] Make Operand immutable
> 
> This CL removes all setters from the Operand and removes the friendship
> relation between Assembler and Operand. All data fields of the Operand
> are set exactly once in the constructor, the Operand is immutable
> afterwards.
> In order to construct the data of an Operand easily, the OperandBuilder
> is introduced. After building an Operand, the data is copied to the
> const field of the Operand.
> 
> R=​mstarzinger@chromium.org
> 
> Bug: v8:7310
> Change-Id: I1628052b8a0c47cbfbc3645dfdac5a0e9705977b
> Reviewed-on: https://chromium-review.googlesource.com/936741
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#51563}

TBR=mstarzinger@chromium.org,clemensh@chromium.org

Change-Id: I8ae40de35e81765549f93ffe58f1b12286de6333
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:7310
Reviewed-on: https://chromium-review.googlesource.com/936627Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51564}