[JDK-8257234](https://bugs.openjdk.java.net/browse/JDK-8257234) added a lot more subtests to this test, so now it sometimes times out. I've double the amount of time given to 240. I'd like to push this as a trivial change.
------------- Commit messages: - Give ClhsdbDumpheap.java a longer timeout since it run a lot more subtests now and sometimes times out. Changes: https://git.openjdk.java.net/jdk/pull/2981/files Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2981&range=00 Issue: https://bugs.openjdk.java.net/browse/JDK-8263477 Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod Patch: https://git.openjdk.java.net/jdk/pull/2981.diff Fetch: git fetch https://git.openjdk.java.net/jdk pull/2981/head:pull/2981 PR: https://git.openjdk.java.net/jdk/pull/2981
