bug 152790

tis620-2 is not defined as th language group
added tis620-2=th into charsetData.properties
r=ftang,sr=sfraser

intl/uconv/src/charsetData.properties

@@ -93,6 +93,7 @@ koi8-r.LangGroup                   = x-cyrillic
 koi8-u.LangGroup                   = x-cyrillic
 shift_jis.LangGroup                = ja
 tis-620.LangGroup                  = th
+tis620-2.LangGroup                 = th
 us-ascii.LangGroup                 = x-western
 utf-16be.LangGroup                 = x-unicode
 utf-16le.LangGroup                 = x-unicode