RFR: 8284548: Invalid XPath expression causes StringIndexOutOfBoundsException [v2]

[Joe Wang]

> Patch note:
> 
> A previous patch had a bug that missed the boundary check, that will cause StringIndexOutOfBoundsException to be thrown instead of XPathExpressionException as expected.
>     
> Fix: the fix is to check the boundaries of the parameter "index". Objects.checkIndex is removed as it's redundant.

Joe Wang has updated the pull request incrementally with one additional commit since the last revision:

  add the test

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8323/files
  - new: https://git.openjdk.java.net/jdk/pull/8323/files/4205ea6f..17b8c3e6

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8323&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8323&range=00-01

  Stats: 82 lines in 1 file changed: 82 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8323.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8323/head:pull/8323

PR: https://git.openjdk.java.net/jdk/pull/8323