RFR: 8278825: Unused variable for diagnostic in Resolve

[Liam Miller-Cushon]

The change removes an unused variable that was left over after [JDK-8067883](https://bugs.openjdk.java.net/browse/JDK-8067883).

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Commit messages:
 - 8278825: Unused variable for diagnostic in Resolve

Changes: https://git.openjdk.java.net/jdk/pull/6841/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6841&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8278825
  Stats: 3 lines in 1 file changed: 0 ins; 3 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6841.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6841/head:pull/6841

PR: https://git.openjdk.java.net/jdk/pull/6841