This changes remoteObjectId format from
"{injectedScriptId:123,id:456}" to "<isolateId>.<contextId>.<id>".

Prepending isolateId fixes the problem that
remote object ids clash between processes. This is especially
troubling during cross-process navigation in Chromium, see bug.

We also stop producing and parsing unnecessary json for object ids.

Drive-by: fixed some tests dumping object ids. Most tests avoid
dumping unstable values like ids, but there were few that still did.

BUG=chromium:1137143

Change-Id: Ia019757fb95704ccb718d3ea6cc54bde1a133382
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2461731
Commit-Queue: Dmitry Gozman <dgozman@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70592}