8142493: Utility methods to check indexes and ranges doesn't specify behavior when function produces null

[Paul Sandoz]

Hi,

Please review:

  
http://cr.openjdk.java.net/~psandoz/jdk9/JDK-8142493-checkIndex-function-return-null/webrev/
 
<http://cr.openjdk.java.net/~psandoz/jdk9/JDK-8142493-checkIndex-function-return-null/webrev/>

This catches some edge cases for the exception mapping function passed to the 
Objects::checkIndex* methods, specifically if the function returns null or 
throws an exception.

Paul.