port 6768456d (r38395)

  original commit message:
  The old code was using VariableMode, but that signal is both
  over-pessimistic (some CONST and LET variables need no hole-initialization)
  and inconsistent with other uses of the InitializationFlag enum (such
  as %LoadLookupSlot).

  This changes no observable behavior, but removes unnecessary hole
  initialization and hole checks in a few places, including
  block-scoped function declarations, super property lookups,
  and new.target.

BUG=

Review-Url: https://codereview.chromium.org/2223803002
Cr-Commit-Position: refs/heads/master@{#38468}