Fixed toggle cheatsheet not working on component editors.
STUD-1514
remove location of item from loc_mapper and cache
Merge pull request #3368 from edx/waheed/stud1514-toggle-cheatsheet-not-working

Fixed toggle cheatsheet not working on component editors.
Merge pull request #3250 from edx/zub/bugfix/std1441-editdiscussioncomp

remove location of item from loc_mapper
Add several acceptance tests for start-time and end-time.
Fix tests.
Updated comments.
Added comments in JS.
Fixing multipple onSeek callbacks calls.
Fix bug.
Fixing bug.
Fixing bug.
Fixing bug.
Fixing bug.
Fix.
Fix.
Fix.
Fix.
Fix.
Fix.