Code review request, 8020842 IDN do not throw IAE when hostname ends with a trailing dot

[Xuelei Fan]

Hi,

Please review the bug fix to strict the illegal input checking in IDN.

webrev: http://cr.openjdk.java.net./~xuelei/8020842/webrev.00/

Here is two test cases, which are expected to get IAE.

Case 1:
String host = IDN.toASCII(".", IDN.USE_STD3_ASCII_RULES);
Exception in thread "main" java.lang.StringIndexOutOfBoundsException:
String index out of range: 0
        at java.lang.StringBuffer.charAt(StringBuffer.java:204)
        at java.net.IDN.toASCIIInternal(IDN.java:279)
        at java.net.IDN.toASCII(IDN.java:118)

Case 2:
String host = IDN.toASCII("com.", IDN.USE_STD3_ASCII_RULES);

Thanks,
Xuelei