Added constructor call on object in InstantiateObject method

Added constructor call on object in InstantiateObject method

I found after upgrading from 4.2.2 where apinatives.js still
existed to 4.4.56 where everything had been converted to C++ in
api-natives.cc, my constructors for ObjectTemplate instantiated objects
were no longer being called.  After investigation, I noticed in
apinatives.js that a new call would handle that, but there was no
corresponding constructor call in api-natives.cc (or anywhere else
along the chain of InstantiateObject), so I added a call to
Execution::Call to actually construct the object.  Forgive me if that
isn't the right place to add it (InitializeBody in objects-inl.h also
looked like a good place), or if there's a reason constructors are
not being called.

I also added myself to the AUTHORS file in this CL.

Review URL: https://codereview.chromium.org/1137693003

Cr-Commit-Position: refs/heads/master@{#29076}