Restore font-family order on Linux and Mac to that before b=425367 change to see if that fixes reftest failures for bugs/414123.xhtml and mathml/mi-mathvariant-1.xhtml.

modules/libpref/src/init/all.js

@@ -852,7 +852,7 @@ pref("intl.locale.matchOS",                 false);
 pref("intl.fallbackCharsetList.ISO-8859-1", "windows-1252");
 pref("font.language.group",                 "chrome://global/locale/intl.properties");
 
-pref("font.mathfont-family", "STIXNonUnicode, STIXSize1, STIXGeneral, Standard Symbols L, DejaVu Sans, Cambria Math");
+pref("font.mathfont-family", "STIXNonUnicode, STIXSize1, STIXGeneral, Cambria Math, Standard Symbols L, DejaVu Sans");
 
 // Some CJK fonts have bad underline offset, their CJK character glyphs are overlapped (or adjoined)  to its underline.
 // These fonts are ignored the underline offset, instead of it, the underline is lowered to bottom of its em descent.
@@ -1764,7 +1764,7 @@ pref("font.size.variable.zh-HK", 15);
 pref("font.size.fixed.zh-HK", 16);
 
 // Apple's Symbol is Unicode so use it
-pref("font.mathfont-family", "STIXNonUnicode, STIXSize1, STIXGeneral, Symbol, DejaVu Sans, Cambria Math");
+pref("font.mathfont-family", "STIXNonUnicode, STIXSize1, STIXGeneral, Cambria Math, Symbol, DejaVu Sans");
 
 // individual font faces to be treated as independent families
 // names are Postscript names of each face