Otherwise, v8 embedders need to depend on targets in src.

BUG=chromium:688155

Change-Id: Idea90d8f550cd4d0141b92a7bdd18f4df664d11b
Reviewed-on: https://chromium-review.googlesource.com/447845Reviewed-by: Marja Hölttä <marja@chromium.org>
Commit-Queue: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43631}