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 base code to 'using' declarations.

R=mlippautz@chromium.org

Bug: v8:8834
Change-Id: Ic5c3d7fa2e50938c6f43e9ff304dc2289fed1133
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1547650Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60546}