Image selection flickers in MS Edge (Upgrade TinyMCE dependency to 4.7.13)

Description

Steps to reproduce:
1. Use the MS Edge browser.
2. Open Alloy Plan.
3. Click an image in the Main body XHTML area.

Expected:
Image should be selected and show the "Go to media" button.

Actual:
Selection flickers and becomes unselected. No "Go to media" button is shown.

This is fixed in TinyMCE 4.7.13 so we need to upgrade our dependency.
https://www.tinymce.com/docs/changelog/?ctrl#version4713may162018