New tests added for:
  * Runtime.getProperties while debugger is paused
  * Runtime.exceptionThrown
  * Runtime.releaseObject/releaseObjectGroup

Change-Id: I72b3455e9fb3269c097bf9a383187c119158a722
Reviewed-on: https://chromium-review.googlesource.com/c/1490172
Commit-Queue: Jeff Fisher <jeffish@microsoft.com>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59984}