Fixes cursor selection for renaming files

In IE 10/11, when renaming a file (in New Files),
you were unable to select inside the text box that
appears when you're renaming a file or folder.
This fixes that bug.

fixes CNVS-16389

test plan:
Pre-requisite: Turn on the "Better File Browsing" feature flag
* Go to any course's Files page (in IE 10, 11)
* Select a file in the file pane
* Click the cog icon on the file item row
* Click "Edit Name"
* Try to click in the textbox that appears for the file you are renaming
* You should be able to click inside the textbox and have your cursor set where you clicked

Change-Id: Ic80f10a2caa3e154521984d9284516d698076bd6
Reviewed-on: https://gerrit.instructure.com/43549
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Clay Diffrient <cdiffrient@instructure.com>
QA-Review: Jahnavi Yetukuri <jyetukuri@instructure.com>
Product-Review: Ryan Shaw <ryan@instructure.com>
Reviewed-by: Ryan Shaw <ryan@instructure.com>