{RegisterConfiguration} is not used inside assembler.h.
Instead, include it where needed.

R=mstarzinger@chromium.org

Bug: v8:8238, v8:7490
Change-Id: Ic1aca23e862c30f5b5c7d13b866a859f1a4d4803
Reviewed-on: https://chromium-review.googlesource.com/c/1340244
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57601}