Review request for JDK-8012291: NativeArray is inconsistent in using long for length and index in some places and int for the same in other places

[Hannes Wallnoefer]

Please review JDK-8012291: NativeArray is inconsistent in using long for 
length and index in some places and int for the same in other places:

http://cr.openjdk.java.net/~hannesw/8012291/

A lot of the noise in the patch is due to the fact that the throwing 
ArrayIndex.getArrayIndex() methods were never used so I removed them and 
let the getArrayIndexNoThrow take their place.

I described the other changes in this comment: 
https://jbs.oracle.com/bugs/browse/JDK-8012291?focusedCommentId=13333243&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13333243

thanks,
Hannes