Javac now uses character offset to store source file positions. But CharacterRangeTable
still uses packed integers to store source file ranges, which hold the line and column
position. The packed integers suffer from overflow problem. Very long source files or
files with very wide columns can overrun the fields in the packaged integer. 

It is better to use character offset to represent CharacterRangeTable's ranges. For
compatibility reason, a new alternative attribute may be introduced.