Double-click on bar in the following: foo bar.

Result with Firefox:

• With Firefox 52.9.0, foo and lots of spaces, including newlines, are also selected.
• With Firefox Nightly 61.0.1, foo bar is selected (with only one space before each word).

Expected result: only the word bar should be selected.

Bug report: bug 637895 (see also bug 1232322).

Double-click on foo in the following:

foo

Result with Firefox 105.0.1 and 123.0.1: foo is selected, with a space before and after the word.