This CL contains a basic Json parser used to read and write the
Json-RPC messages of the language server protocol.

This CL is part of the initial language server implementation but
submitted separately for easier review.

R=tebbi@chromium.org

Bug: v8:8880
Change-Id: Icea040975e1ed1d587954c3342d8d876e01c26b8
Reviewed-on: https://chromium-review.googlesource.com/c/1479956
Commit-Queue: Simon Zünd <szuend@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59848}