Cross Origin issue

**Describe the bug**
getting following error in browser console when marking down empty cell.
Access to font at 'about:blank' from origin 'http://localhost:8888' has been blocked by CORS policy: Cross origin requests are only supported for protocol schemes: http, data, chrome, chrome-extension, chrome-untrusted, https.

GET about:blank net::ERR_FAILED

**To Reproduce**
Steps to reproduce the behavior:
1. open new jupyter notebook.
2. Mark down empty cell , (cell--> cell type--> Markdown)
3. open browser console to check CORS error.

**Expected behavior**
No error expected in console.

**Screenshots**

**Desktop (please complete the following information):**
- OS: Windows 10
- Browser chrome
- Version 6.1.1

**Additional context**
on running the marked down cell, able to get following output.

Type Markdown and LaTeX: 𝛼2

Reproduce the issue in a new Jupyter Notebook using Chrome, convert an empty cell to Markdown, and inspect the browser console. Trace the console request associated with the empty Markdown cell; done means the CORS and about:blank errors no longer appear.

Written by the indexing model from the issue text.