Please provide math fonts mentioned at http://www.mozilla.org/projects/mathml/fonts/. $ unzip ~/tmp/MathFonts_TrueType.exe $ unzip ~/tmp/texcm-ttf.zip (these maybe overlap with tetex?) Check for example http://www.w3.org/Math/testsuite/testsuite/Presentation/TokenElements/mo/moAaccent9.xml for result.
https://bugzilla.mozilla.org/show_bug.cgi?id=128153#c81
Mozilla is dead upstream and will be removed from portage.