Multi styled text runs together due to spaces being trimmed.

This is in relation to an issue I posted last year: 
https://github.com/dompdf/dompdf/issues/475

At first it seemed like a font metric but is due to text_frame_reflower right trimming strings in cases where a tag is in a tag.  Example:
<p><b>THIS IS BOLD, <u>UNDERLINED AND <i>ITALIC</i></u></b></p>
becomes
<p><b>THIS IS BOLD,<u>UNDERLINED AND<i>ITALIC</i></u></b></p>
This same problem seems to have been commented out in the past regarding left trimmed strings which is visible just a few lines down from the one I commented out.