Debugging API is still in use by Node.

Revert "[debug] remove deprecated debug command message queue."
This reverts commit abdbfc95.

Revert "[debug] mark more unused debug API as deprecated."
This reverts commit d5ada19c.

BUG=v8:5530

Review-Url: https://codereview.chromium.org/2537313005
Cr-Commit-Position: refs/heads/master@{#41427}