RFR: 8284400: Improve XPath exception handling

[Naoto Sato]

On Fri, 27 May 2022 01:12:18 GMT, Joe Wang <joehw at openjdk.org> wrote:

> Addresses an insufficiency of error handling in the XPath implementation. Some cleanup where appropriate, without attempting to do too much as this is a component that hasn't had much changes for 15 years, a fairly stable application.
> 
> Test: tier2 passed
> JCK: JCK XML tests passed

LGTM. Nit: some files have old copyright years and/or `@LastModified` fields

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Marked as reviewed by naoto (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/8910