Support for Screen Reader

(Bug #104477, r=price, sr=dveditz)

xpinstall/packager/windows/install.it

@@ -51,6 +51,8 @@ DELETE_=&Delete
 README=Re&ad Me
 PAUSE_=&Pause
 RESUME_=&Resume
+CHECKED=Checked
+UNCHECKED=Unchecked
 
 EXTRACTING=Extracting...