Even though both are allowed in the style guide, it recommends to use
'using', as its syntax is more consistent with the rest of C++.
This CL turns all typedefs in ic code to 'using' declarations.

R=ishell@chromium.org

Bug: v8:8834
Change-Id: I70c74d3f20a6c15693157de5fc40bb769ef0599d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1545895
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60520}