That code (i8 := 0xFF) should not be accepted, though n8 := 0xFF should.
If you want to deal with bit patterns, isn't that what naturals are for?

Note also that "the bit pattern of the integer" is not well-defined anyway,
since there are several possible representations of an integer
(ones complement, twos complement, sign magnitude).  See for example

   http://nssdc.gsfc.nasa.gov/nssdc/formats/IntegerNumbers.htm

If your code is really dealing with integers and you specify 0xFF
and it is interpreted as a bit pattern, then you won't get the value
you expect on a ones-complement machine.  Unless you mean that the compiler
is interpreting 0xFF as a bit pattern in two's complement notation,
in which case you would get the expected value of -1.

But again, I think having the semantics of a constant depend on context
is a very bad idea.  Anyway, I'll let the ECMA committee sort this out.