Text Only - Print Driver No Longer Working?

For many years, I've used the Generic / Text Only virtual printer driver to convert Web pages and other files to plain text with minimal formatting, but the last time I used it, the resulting file was peppered with unnecessary spaces, making it close to indecipherable when viewed in a text editor. Has some recent update changed the way this driver works (or, in my case, doesn't work)?

I've attached two files to illustrate the problem: filler.html contains a few paragraphs of boilerplate text, and filler.prn is the result I get from loading filler.html into Firefox and printing it to the Text Only "printer". (Both files were renamed to filler.*.txt to conform to this forum's limitations for uploaded files.) Note that the output file is more than ten times the size of the input file; if you examine it with a hex editor, you'll see that the increased size of the output is due to many sequences of a carriage return (without a linefeed) and several spaces being unnecessarily inserted in the output stream every few characters.

I imagine if this were sent to a 1970s-era printer, the defects in the output would be invisible on the page, but since the whole point of the Text Only driver is to bypass any physical printer, I don't understand this change in behavior. Is there any way to prevent this and get back to the output I'm used to?