Reland of: [code coverage] Add all fuzzer targets

Now with a fix for the issue in GenerateIsolates().

R=jbudorick,stgao,liaoyuke

> Change-Id: I78ffec6525cd1d808a4b431ae1e2729b76357d46
> Reviewed-on: https://chromium-review.googlesource.com/c/1372917
> Commit-Queue: Shuotao Gao <stgao@chromium.org>
> Reviewed-by: Shuotao Gao <stgao@chromium.org>
> Reviewed-by: John Budorick <jbudorick@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#615834}

Change-Id: I4ae0ef2588026bb6e0e5501e9ff39a7852d89afa
Reviewed-on: https://chromium-review.googlesource.com/c/1374777
Reviewed-by: Yuke Liao <liaoyuke@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Roberto Carrillo <robertocn@chromium.org>
Cr-Commit-Position: refs/heads/master@{#616169}
7 files changed