Firefox 24 MathML Release Notes

Firefox 24 is released this week. A few release notes:

* Firefox 24
   - Using the dir attribute is now equivalent to using the CSS 
"direction" property
   - The equal sign '=' is now stretchable
   - New menclose notation "updiagonalarrow"

* Firefox 26. Improvements to the script elements by James Kitchener:
   - The rendering of msup, msubsup and mmultiscripts is now identical 
for equivalent configurations.
   - A bug causing incorrect application of the subscriptshift and 
superscriptshift attributes for msup, msubsup and mmultiscripts has been 
fixed.
   - Better error reports.

I'm also repeating the report for Firefox 23 since I didn't send release 
notes:

* Firefox 23
   - Complete support for the <semantics> element
   - Better support for <mspace> with negative width

As usual, the detailed list of bug entries can be found at
https://wiki.mozilla.org/MathML:Home_Page#Last_bugs_fixed