I don't agree.  I believe ECMA specifies that an Integer (no sign)
can be written in decimal, hexadecimal or octal, with the same
semantics.  Therefore 0xFF is 255.  It is only at the level of
Signed_integer (or whatever it is called) that the sign comes into
play.

Note also that in rev 68843

   print ({INTEGER_8} 0xFF)      prints -1
   print ({INTEGER_8} -0xFF}     gives integer too large compile error

I don't think it is the intention of ECMA that the value of 0xFF
depend on the context.  I think it is always 255.  Please see
section 8.32.30 for the semantics of Integer.