Replace direct calls to generated code with calls using GeneratedCode to
match the rest of v8.

BUG=v8:7164

Change-Id: I5d90bcb6e90d99e105be18886d4844b83f611b95
Reviewed-on: https://chromium-review.googlesource.com/1000416Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52467}