There are two places where RecordWrite code stub is called,
OutOfLineRecordWrite and RecordWriteField. With this commit, if
`v8_enable_csa_write_barrier` flag is turned on, no instances of the old
RecordWrite stub appear in the snapshot.

Bug: chromium:749486
Change-Id: I2bc3fa38c8831736303b46d153a79c034a450f16
Reviewed-on: https://chromium-review.googlesource.com/648983
Commit-Queue: Albert Mingkun Yang <albertnetymk@google.com>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48004}