RFR: 8248381: Create a daemon thread for MonocleTimer [v2]

[John Neffenger]

> Fixes [JDK-8248381](https://bugs.openjdk.java.net/browse/JDK-8248381).

John Neffenger has updated the pull request incrementally with one additional commit since the last revision:

  Remove POOL_SIZE constant

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Changes:
  - all: https://git.openjdk.java.net/jfx/pull/256/files
  - new: https://git.openjdk.java.net/jfx/pull/256/files/c771c242..4ca2bc03

Webrevs:
 - full: https://webrevs.openjdk.java.net/jfx/256/webrev.01
 - incr: https://webrevs.openjdk.java.net/jfx/256/webrev.00-01

  Stats: 2 lines in 1 file changed: 0 ins; 1 del; 1 mod
  Patch: https://git.openjdk.java.net/jfx/pull/256.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/256/head:pull/256

PR: https://git.openjdk.java.net/jfx/pull/256