It's a little cleanup: make sure `frame` is accessed from EDT only, remove unused variables and imports.
------------- Commit messages: - JDK-8277396: [TESTBUG] In DefaultButtonModelCrashTest.java, frame is accessed from main thread Changes: https://git.openjdk.java.net/jdk/pull/6455/files Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6455&range=00 Issue: https://bugs.openjdk.java.net/browse/JDK-8277396 Stats: 13 lines in 1 file changed: 4 ins; 5 del; 4 mod Patch: https://git.openjdk.java.net/jdk/pull/6455.diff Fetch: git fetch https://git.openjdk.java.net/jdk pull/6455/head:pull/6455 PR: https://git.openjdk.java.net/jdk/pull/6455
