Remove support for Netscape 4 from kses.php (because it's 2012)

[Ipstenu]

Futzing around, I ran into this in kses.php

​http://core.trac.wordpress.org/browser/tags/3.3.1/wp-includes/kses.php#L995

Removes the HTML JavaScript entities found in early versions of Netscape 4.

Reading it, if that's really true and the only reason it's needed, I think we're pretty safe in removing it now.

Patch added.

[Ipstenu]

Removing netscape 4 stuff

[mbijon]

I shouldn't, but...

+1 on pulling this without a deprecation step

[Ipstenu]

Refreshing patch because it's now 2014.

[Ipstenu]

Refreshing patch because it's now 2014.

[nacin]

As this is there for security reasons, its age may not be enough to remove these. What do these HTML entities look like? Do any other browsers also recognize them? Is this still a concern in the security community?

Applying this patch specifically breaks one of our unit tests based on ​http://ha.ckers.org/xssAttacks.xml. (The first one, in fact.) Sounds like "invalid" to me.

[Ipstenu]

Well if it breaks that then yeah :)

[dmsnell]

Recreated in #33848 because I did not find this ticket when I opened the new one.

@nacin: It has been difficult for me to find out definitely if this impacts any browser within the past ten years, but the initial answer appears to be that it does not.

The thing that I'm most uncertain of is how to verify that, but I believe that if we constructed a white hat XSS vulnerability and tested it across the varying platforms we could have a definitive answer.