Integrated: Primitive value conversion

[Vicente Romero]

Warn on primitive value conversion

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Commit messages:
 - primitive value conversion

Changes: https://git.openjdk.java.net/valhalla/pull/575/files
 Webrev: https://webrevs.openjdk.java.net/?repo=valhalla&pr=575&range=00
  Stats: 31 lines in 4 files changed: 28 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/575.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/575/head:pull/575

PR: https://git.openjdk.java.net/valhalla/pull/575