Before the fix it checked whether the initial map of the base constructor pointed back to the new target. That's only true if initial_map->new_target_is_base() (new.target == target). Now it properly checks that the initial map of the original constructor (new.target) was created in combination with target by checking back that new.target->initial_map()->constructor() == target.

BUG=

Review-Url: https://codereview.chromium.org/2621303003
Cr-Commit-Position: refs/heads/master@{#42263}