This patch:
- teaches Runtime.callFunctionOn to accept executionContextId instead of
  objectId.
- adds the optional objectGroup parameter to the Runtime.callFunctionOn.

R=kozy

Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Ia29ee37f37a1e8cbe2d9f15ae75e841534ecf727
Reviewed-on: https://chromium-review.googlesource.com/639751Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
Reviewed-by: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Commit-Queue: Andrey Lushnikov <lushnikov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47659}