RFR: JDK-8285610: TreeInfo.pathFor and its uses appear to be dead code

[Jonathan Gibbons]

Please review a trivial change to remove some unused/dead code. 

All tier1 tests pass.

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Commit messages:
 - JDK-8285610: TreeInfo.pathFor and its uses appear to be dead code

Changes: https://git.openjdk.java.net/jdk/pull/8393/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8393&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8285610
  Stats: 42 lines in 2 files changed: 0 ins; 42 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8393.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8393/head:pull/8393

PR: https://git.openjdk.java.net/jdk/pull/8393