javac accepts unicode digits in many contexts in which the spec
requires that it only accept ASCII digits.
(1) in integral constants, after the first digit
(2) in floating point literals, after the first digit
(3) in unicode character constants
(1) and (3) are fairly harmless, but (2) causes the compiler to crash.
javac will now warn when non-ASCII digits are used where ASCII digits
Because of the incompatibility, this bug cannot be fully fixed until a
"dot" release such as 1.5. But the crash should be addressed earlier.