RFR: 8254369: Node::disconnect_inputs may skip precedences

[Xin Liu]

8254369: Node::disconnect_inputs may skip precedences

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

Commit messages:
 - 8254369: Node::disconnect_inputs may skip precedences

Changes: https://git.openjdk.java.net/jdk/pull/664/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=664&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8254369
  Stats: 18 lines in 2 files changed: 15 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/664.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/664/head:pull/664

PR: https://git.openjdk.java.net/jdk/pull/664