This reduces the build steps from touching api.h: 269 -> 156

BUG=v8:7754,v8:7490

Change-Id: I75abaeea4cc78027a47304ff9b9f6b12bdb2b75e
Reviewed-on: https://chromium-review.googlesource.com/1144929Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54583}