What steps will reproduce the problem?
1. Edit a javascript file with js2-mode.
2. Edit some other file with default-generic-mode.

What is the expected output? What do you see instead?
I expect to see comments in the default-generic buffer start at a # and end
at the end of the line.  Instead, they start at a # but continue all the
way to the end of the buffer.

What version of the product are you using? On what operating system?
js2-20080616.el with emacs-22.2.

Please provide any additional information below.
Default-generic-mode works as expected until js2-mode is used.