Update opaque-keys library
Merge pull request #4410 from edx/sarina/update-deprecation-warnings

Update opaque-keys library
Add "visible_to_staff_only" field to support staff locking in Studio.

STUD-1875
Implement close_connections and drop_database on modulestores.
Merge pull request #4402 from edx/christina/staff-lock

Add "visible_to_staff_only" field to support staff locking in Studio.
Merge pull request #4370 from edx/nimisha/split-drop-database-2952

Implement close_connections and drop_database on modulestores.
Add defininition of window.location.origin in both CMS/LMS

The same bug in studio was fixed in #3893, and as TinyMCE is also used in LMS, it should be also fixed in LMS.
Here a common javascript file called 'ie_shim.js' is added, so that in the future it can be used for other IE compatibility purposes too.