The main change here is that in isolate-data.h, I'm switching from stateJSON to state.
This routine returns a CBOR encoded state cookie, which is also what we already
use in Chromium (blink).

In inspector-test.cc, I then put this byte vector into a V8 String,
and to make this roundtrip, change the extraction routine to get the
bytes. It's a little weird to store arbitrary bytes inside a v8 string,
but it appears to work fine because these bytes end up in the 8 bit portion,
much like isolatin characters would.

Change-Id: I72a0bdefd85a290f4e91db79be67d86952831685
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1610478Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Alexei Filippov <alph@chromium.org>
Commit-Queue: Johannes Henkel <johannes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61544}