For non-simple param lists, the parser first declares a TEMPORARY for each
param, and then the named variables as locals. The TEMPORARY variables determine
the parameter count.

This CL makes the PreParser produce the same parameter count as the Parser.

BUG=v8:5516

Change-Id: I8a794d6a8342145ab7934d922e2d69450d67b199
Reviewed-on: https://chromium-review.googlesource.com/517944
Commit-Queue: Marja Hölttä <marja@chromium.org>
Reviewed-by: Daniel Vogelheim <vogelheim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45566}