Selecting text on a table header row does not work

Issue Summary

Trying to select text from a single Header Row Cell does not work. We need to either select nothing or all header cells.

Steps to Reproduce

1. Create a page using the Old Editor (Legacy, tinyMCE)
2. Insert a table with header row
3. Try to select the text within that header row

Expected Results

Only the desired text is highlighted

Actual Results

No text is highlighted or every header cell is highlighted.

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available