RFR: 8277906: Incorrect type for IV phi of long counted loops after CCP

[Roland Westrelin]

This failure occurs because the iv phi of a long counted loop has the
wrong type after CCP. That happens because, during CCP, after the type
of the limit of the counted loop is updated, the type of the iv phi is
not recomputed. The fix is to apply to long counted loops the logic
that already exists for int counted loop.

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Commit messages:
 - test
 - fix

Changes: https://git.openjdk.java.net/jdk/pull/6632/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6632&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8277906
  Stats: 66 lines in 2 files changed: 61 ins; 0 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6632.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6632/head:pull/6632

PR: https://git.openjdk.java.net/jdk/pull/6632