port 12bcba15 (r33258)

  original commit message:
  The API functions are always in sloppy mode, so receiver is always a
  JSReceiver once the actual call trampoline runs, no need to check again
  in various places.

BUG=

Review URL: https://codereview.chromium.org/1582173002

Cr-Commit-Position: refs/heads/master@{#33278}