Bug 1088179 - Convert touch caret code to using :-moz-native-anonymous so that it doesn't expose styles for magic attribute names to content.  r=birtles

I tested locally on a Flame that using this without the ua.css changes
breaks the touch caret (it doesn't appear), but with the ua.css changes
the touch caret appears again.

This was formerly bug 1082899 patch 6.

--HG--
extra : transplant_source : %CA%60%B7%10%AD%01%14%92%98%28o%AA%BF%5E%8F%7BV%AA%24%D5