RFR: JDK-8267690: Revisit (Doc)Tree search implemented by throwing an exception [v2]

[Jonathan Gibbons]

> Please review a moderately simple cleanup change, to eliminate using an exception to terminate scanning a `Tree` or `DocTree` in `(Doc)TreePath.getPath`.
> 
> The change is to set a field with the intended result, and once that field is set, do "best-effort" to eliminate any addition scanning.
> 
> It is easy enough to stop scanning items in a list, but it is not practical to totally stop scanning the subsequent sibling nodes, but we can substantially reduce the cost of scanning those nodes, and can definitely avoid scanning any children of those nodes.

Jonathan Gibbons has updated the pull request incrementally with one additional commit since the last revision:

  improve parameter naming for internal `PathFinder` classes

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8369/files
  - new: https://git.openjdk.java.net/jdk/pull/8369/files/32aab7f0..0858b41f

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8369&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8369&range=00-01

  Stats: 8 lines in 2 files changed: 0 ins; 0 del; 8 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8369.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8369/head:pull/8369

PR: https://git.openjdk.java.net/jdk/pull/8369