Building cctest has linking error when gn's args has "is_component_build = true".
This CL make the visibility of "MemOperand" and "UseScratchRegisterScope" from
"hidden" to "default" to solve this problem.

Change-Id: I3ebfaa25d598b4f2d626861b947c93d111d95456
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1731213
Auto-Submit: Mu Tao <pamilty@gmail.com>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63062}