* [indic] Add support for Grantha marks that may be used in Tamil to the Indic table.
See https://bugzilla.mozilla.org/show_bug.cgi?id=1331339.
Testcase: U+0BA4,U+0BC6,U+1133c,U+0BAA,U+1133c,U+0BC6,U+1133c
* [indic] Add test for Grantha nukta that is allowed in Tamil by ScriptExtensions.txt
jfkthame