[parser] Skipping inner funcs: make preparser scope analysis test work w/ destructuring declarations.

If hidden scopes are ignored, the scopes and variable produced by the PreParser
already matched the scopes and variables produced by the Parser.

BUG=v8:5516
R=vogelheim@chromium.org

Review-Url: https://codereview.chromium.org/2663043003
Cr-Commit-Position: refs/heads/master@{#42824}