RFR: 8247494: Test failure in ImageRaceTest on some systems

[Pankaj Bansal]

The test test.com.sun.javafx.image.impl.ImageRaceTest is fails intermittently in linux

This is caused by use of Thread.yield. Thread.yield is used to tell pause the current thread for some time. It gives a hint to thread scheduler that the current thread should pause and other threads with same or higher priority should execute. But it is a hint only and can be ignored. so the current thread may very well continue to operate. This causes the test to fail on some slow machines.

Better approach in this scenario would be to use Thread.sleep to make the thread for some time for some event.

-------------

Commit messages:
 - 8247494: Test failure in ImageRaceTest on some systems

Changes: https://git.openjdk.java.net/jfx/pull/332/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=332&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8247494
  Stats: 8 lines in 1 file changed: 6 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jfx/pull/332.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/332/head:pull/332

PR: https://git.openjdk.java.net/jfx/pull/332