The code fields in a JSRegExp object now either contain irregexp
compiled code or a trampoline to the interpreter. This way the code
can be executed without explicitly checking if the regexp shall be
interpreted or executed natively.
In case of interpreted regexp the generated bytecode is now stored in
its own fields instead of the code fields for Latin1 and UC16
respectively.
The signatures of the jitted irregexp match and the regexp interpreter
have been equalized.

Bug: v8:9516
Change-Id: I30e3d86f4702a902d3387bccc1ee91dea501fe4e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1762513
Commit-Queue: Patrick Thier <pthier@google.com>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63457}