Prevent IE from editing ce="false"

This is a redux of logic already in master.
Moved from keydown to keypress because IE
fires keydown multiple times for held keys.
Changed the logic to determine that the current
offset is just after an element that should not be
directly edited.

Change-Id: I5206d8919abde740d92f636b0c8618c4ebb6f6ff
Merge "Prevent IE from editing ce="false""