This is a reland of 5b744bfb.
Node is fixed by this pull request:
https://github.com/v8/node/pull/75

Original change's description:
> Fix and extend lldbinit
>
> 1) Define all commands in one file.
> 2) Add logic to make 'jco' print current pc by default.
> 3) Add a comment to explain how to load the lldb_commands.py file.
> 4) Minor refactorings.
>
> R=ahaas@chromium.org
> No-Try: true
>
> Bug: v8:7754
> Change-Id: I553f2ce4cefedad05466c692a8665a570372b76a
> Reviewed-on: https://chromium-review.googlesource.com/1127892
> Reviewed-by: Andreas Haas <ahaas@chromium.org>
> Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#54329}

Bug: v8:7754
Change-Id: I8645ae07176fe6983a581dd175ed6f2b2b15d4ea
Reviewed-on: https://chromium-review.googlesource.com/1135026Reviewed-by: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54424}