RFR: 8273704: DrawStringWithInfiniteXform.java failed : drawString with InfiniteXform transform takes long time

[Phil Race]

This test has only failed once - for reasons that are not clear.
I wanted to just increase the timeout but the test was written such that it always waited as long
as the timeout since it had an un-canceled scheduled task.

So I've also made the test cancel the task once it is complete and made the variables volatile
so that they should be read properly by the other thread.

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Commit messages:
 - 8273704: DrawStringWithInfiniteXform.java failed : drawString with InfiniteXform transform takes long time

Changes: https://git.openjdk.java.net/jdk/pull/6087/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6087&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8273704
  Stats: 7 lines in 1 file changed: 3 ins; 1 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6087.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6087/head:pull/6087

PR: https://git.openjdk.java.net/jdk/pull/6087