This is also needed so that PreParser doesn't need to gather more data for arrow
function params in order to create the uninteresting varblock scopes matching
the scopes created in Parser::BuildParameterInitializationBlock.

This cancels the changes in https://chromium-review.googlesource.com/c/444747
which make PreParser create uninteresting scopes for the normal (non-arrow)
function "eval in default param" case.

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

Change-Id: I8957ac0796d8738c63492f7928bca6f00e4b4241
Reviewed-on: https://chromium-review.googlesource.com/446339Reviewed-by: Daniel Vogelheim <vogelheim@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43411}