- See bug for the reduced test case.

- Not adding a regression test here: I don't want to assert that PreParser
  doesn't detect the redeclaration error, OTOH I don't want to make it detect
  the error either (in order to not couple detecting the error with
  FLAG_experimental_preparser_analysis).

BUG=chromium:753896, v8:5516

Change-Id: I0f1beffe30e5cb48d6dbec35181980864e6df153
Reviewed-on: https://chromium-review.googlesource.com/608976Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47326}