The following aspects were changed for the reland:

* The DeferredHandleScope is supposed with a specific pattern,
  i.e. allocate handles in a normal HandleScope and then 
  reopen them in the DeferredHandleScope.
* Set the native_context when it is used in a task.

Change-Id: Ia42c46ec6bc73179cb1f458e36658414ff85cc23
Reviewed-on: https://chromium-review.googlesource.com/468809
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44434}